diff --git a/doc/transceiver-monitor-hld.md b/doc/transceiver-monitor-hld.md
new file mode 100644
index 00000000000..fd1120f3ab3
--- /dev/null
+++ b/doc/transceiver-monitor-hld.md
@@ -0,0 +1,152 @@
+# Transceiver and Sensor Monitoring HLD #
+
+### Rev 0.1 ###
+
+### Revision
+ | Rev | Date | Author | Change Description |
+ |:---:|:-----------:|:------------------:|-----------------------------------|
+ | 0.1 | | Liu Kebo | Initial version |
+
+## About This Manual ##
+
+This document is intend to provide general information about the Transceiver and Sensor Monitoring implementation.
+The requirement is described in [Sensor and Transceiver Info Monitoring Requirement.](https://github.com/Azure/SONiC/blob/gh-pages/doc/OIDsforSensorandTransciver.MD)
+
+
+## 1. Xcvrd design ##
+
+New Xcvrd in platform monitor container is designed to fetch the transceiver and DOM sensor information from the eeprom and then update the state db with these info.
+
+For the transceiver it's self, the type, serial number, hardware version, etc. will not change after plug in. The suitable way for transceiver information update can be triggered by transceiver plug in/out event.
+
+The transceiver dom sensor information(temperature, power,voltage, etc.) can change frequently, these information need to be updated periodically, for now the time period temporarily set to 60s(see open question 1), this time period need to be adjusted according the later on test on all vendors platform.
+
+If there is transceiver and sensor status change, Xcvrd will write the new status to state DB, to store these information some new tables will be added to STATE_DB.
+
+### 1.1 State DB Schema ###
+
+New Transceiver info table and transceiver DOM sensor table will be added to state DB to store the transceiver and DOM sensor information.
+
+#### 1.1.1 Transceiver info Table ####
+
+ ; Defines Transceiver information for a port
+ key = TRANSCEIVER_INFO|ifname ; configuration for watchdog on port
+ ; field = value
+ type = 1*255VCHAR ; type of sfp
+ hardwarerev = 1*255VCHAR ; hardware version of sfp
+ serialnum = 1*255VCHAR ; serial number of the sfp
+ manufacturename = 1*255VCHAR ; sfp venndor name
+ modelname = 1*255VCHAR ; sfp model name
+
+#### 1.1.2 Transceiver DOM sensor Table ####
+
+ ; Defines Transceiver DOM sensor information for a port
+ key = TRANSCEIVER_DOM_SENSOR|ifname ; configuration for watchdog on port
+ temperature = FLOAT ; temperature value in Celsius
+ voltage = FLOAT ; voltage value
+ rx1power = FLOAT ; rx1 power in dbm
+ rx2power = FLOAT ; rx2 power in dbm
+ rx3power = FLOAT ; rx3 power in dbm
+ rx4power = FLOAT ; rx4 power in dbm
+ tx1bias = FLOAT ; tx1 bias in mA
+ tx2bias = FLOAT ; tx2 bias in mA
+ tx3bias = FLOAT ; tx3 bias in mA
+ tx4bias = FLOAT ; tx4 bias in mA
+
+
+### 1.2 Access eeprom from platform container ###
+
+Transceiver information eeprom can be accessed via read files(e.g. `/sys/bus/i2c/devices/2-0048/hwmon/hwmon4/qsfp9_eeprom`), different vendors may have these files under different folders, these folder need to be mounted to platform container so Xcvrd can access them.
+
+
+For the convenience of implementation and reduce the time consuming, need to do enhancement to the `SfpUtilBase` class:
+
+1. `SfpUtilBase` internally should add the ability to read the eeprom and only pick up the interested bytes by given offset and number of bytes.
+
+2. `SfpUtilBase` will provide APIs `get_eeprom_sfp_info_dict(self, port_num)` and `get_eeprom_dom_info_dict(self, port_num)` to return `eeprom_if_dict` and `eeprom_dom_dict` separately, the interested values of these two dict are defined in section 1.1.1 and 1.1.2. In these two APIs can pick up these values from eeprom by provide the corresponding offset and number of bytes.
+
+
+### 1.3 Transceiver plug in/out event ###
+
+Xcvrd need to be triggered by transceiver plug in/out event to refresh the transceiver info table.
+
+How to get this event is various on different platform, there is no common implementation available.
+
+Here we define a common platform API to wait for this event in class `SfpUtilBase`:
+
+ @abc.abstractmethod
+ def get_transceiver_change_event(self, timeout=0):
+ """
+ :param timeout: function will return success and a empty dict if no event in this period, default value 0 means never timeout.
+ :returns: Boolean, True if call successful, False if not;
+ dict for pysical port number and the SFP status, status '1' represent plug in, '0' represent plug out(eg. {'0': '1', '31':'0'})
+ """
+ return
+
+Each vendor need to implement this function in `SfpUtil` plugin.
+
+Xcvrd will call this API to wait for the sfp plug in/out event, following example code showing how this API will be called:
+
+ while True:
+ status, port_dict = platform_sfputil.get_transceiver_change_event()
+ if(status):
+ for key, value in port_dict.iteritems():
+ print("SFP on port: %s" was %s" % (key, value))
+
+It's possible that when received the plug in/out event, the transceiver eeprom is not ready for reading, so need to give another try if first reading failed.
+
+### 1.4 Xcvrd daemon flow ###
+
+Xcvrd will spawn a thread to wait for the SFP plug in/out event, when event received, it will update the DB entries accordingly.
+
+A timer will be started to periodically refresh the DOM sensor information .
+
+Detailed flow as showed in below chart:
+
+
+
+## 2. SNMP Agent Change ##
+
+### 2.1 MIB tables extension ###
+
+MIB table entPhysicalTable from [Entity MIB(RFC2737)](https://tools.ietf.org/html/rfc2737) need to be extended to support new OIDs.
+
+| OID | SNMP counter | Where to get the info in Sonic. | Example: |
+| --- | --- | --- | --- |
+| 1.3.6.1.2.1.47.1.1.1 | entPhysicalTable | | |
+| 1.3.6.1.2.1.47.1.1.1.1 | entPhysicalEntry | | |
+| 1.3.6.1.2.1.47.1.1.1.1.2. index | entPhysicalDescr | Show interfaces alias | Xcvr for Ethernet29 |
+| 1.3.6.1.2.1.47.1.1.1.1.7. index | entPhysicalName | skipped | |
+| 1.3.6.1.2.1.47.1.1.1.1.8. index | entPhysicalHardwareVersion | Vendor Rev in CLI or sfputil | A1 |
+| 1.3.6.1.2.1.47.1.1.1.1.9. index | entPhysicalFirmwareVersion | Skipped | |
+| 1.3.6.1.2.1.47.1.1.1.1.10.index | entPhysicalSoftwareRevision | Skipped | |
+| 1.3.6.1.2.1.47.1.1.1.1.11.index | entPhysicalSerialNum | Vendor SN in CLI or sfputil | WW5062F |
+| 1.3.6.1.2.1.47.1.1.1.1.12.index | entPhysicalMfgName | Vendor Name in CLI or sfputil | FINISAR CORP |
+| 1.3.6.1.2.1.47.1.1.1.1.13.index | entPhysicalModelName | Vendor PN in CLI or sfputil| FCBN410QD3C02 |
+
+
+Another entPhySensorTable which is defined in [Entity Sensor MIB(RFC3433)](https://tools.ietf.org/html/rfc3433) need to be new added.
+
+| OID | SNMP counter | Where to get the info in Sonic. | Example: |
+| --- | --- | --- | --- |
+| 1.3.6.1.2.1.99.1.1 | entPhySensorTable | | |
+| 1.3.6.1.2.1.99.1.1.1 | entPhySensorEntry | | |
+| 1.3.6.1.2.1.99.1.1.1.1.index | entPhySensorType | In CLI: E.g.RX1Power: -0.97dBm | 6 |
+| 1.3.6.1.2.1.99.1.1.1.2.index | entPhySensorScale | Same as above | 8 |
+| 1.3.6.1.2.1.99.1.1.1.3.index | entPhySensorPrecision | Same as above | 4 |
+| 1.3.6.1.2.1.99.1.1.1.4.index | entPhySensorValue | Same as above | 7998 |
+| 1.3.6.1.2.1.47.1.1.1.1.2.index | entPhysicalDescr | Show interfaces alias | DOM RX Power Sensor for DOM RX Power Sensor for Ethernet29/1 |
+
+
+More detailed information about new table and new OIDs are described in [Sensor and Transceiver Info Monitoring Requirement](https://github.com/Azure/SONiC/blob/gh-pages/doc/OIDsforSensorandTransciver.MD#transceiver-requirements-entity-mib).
+
+### 2.2 New connection to STATE_DB ###
+
+To get the transceiver and dom sensor status, SNMP agent need to connect to STATE\_DB and fetch information from TRNASCEIVER_TABLE which will be updated by Xcvrd when this is status change.
+
+
+## 3. Open Questions ##
+
+1. DOM sensor polling period may need to be adjusted after collecting enough data on various platform.
+
+
diff --git a/images/transceiver_monitoring_hld/xcvrd_flow.svg b/images/transceiver_monitoring_hld/xcvrd_flow.svg
index a2c5c85331f..7315df0af14 100644
--- a/images/transceiver_monitoring_hld/xcvrd_flow.svg
+++ b/images/transceiver_monitoring_hld/xcvrd_flow.svg
@@ -1,2 +1,2 @@
-
\ No newline at end of file
+
\ No newline at end of file