The invention is applicable to the field of communication and provides a synchronous data transmission method and device on the basis of Baud rate of communication connectors. The synchronous data transmission method includes generating a Baud rate compensating parameter list corresponding to temperature characteristic values; storing the Baud rate compensating parameter list; detecting the current temperature and generating temperature characteristic values according to the current temperature; calling the corresponding Baud rate compensating parameters from the Baud rate compensating parameter list according to the temperature characteristic values and calculating the current Baud rate count values according to the Baud rate compensating parameters and the acquired reference Baud rate count values; updating the current Baud rate count values to enable communication data to be transmitted according to the updated Baud rate count values. During changing of the temperature, the internal Baud rate count values can be automatically adjusted, so that the communication data can be received and transmitted according to the updated Baud rate count values, synchronous data transmission is guaranteed, integrity during implementation is high, multiple units in the system can be multiplexed, and the device for implementing the method is small in size and low in cost.