Abstract: This paper articulates the importance of control execution time test for coal mine safety monitoring system, for the sensor data transmission system using RS485 bus, this paper presents a method to measure the time of sub-station control execution using data of sensor and control actuator simulated by computer software. The reaction time and action time of the control actuator are measured by the oscilloscope, and the total control execution time is finally obtained. The research shows that this method is faster and more accurate and has better scalability in practical application compared with stopwatch and other tools for testing.