Abstract: Aiming at the problem of improving the communication efficiency of RS485 bus, this paper analyzes the advantages and disadvantages of four measures: increasing baud rate, controlling transceiver control timing, multi-master communication and software improvement communication strategy, and proposes a strategy of group call and queue response for RS485 bus communication. This strategy is a bus communication software strategy, which does not change any hardware, uses group call and sequential response to reduce the number of host calls, sets priority queue to reduce the slave response time, uses simplified coding to reduce the data frame length without changing information, further shortens the polling cycle and greatly improves the communication efficiency. Through the RS485 communication test between substation and sensors, compared with the traditional method, the polling cycle and the response time of sensor transmitting emergency information are greatly shortened.