Abstract: In the complex environment of high humidity and high dust in coal mine, the existing technology of mining wind speed detection is difficult to achieve high precision measurement of low wind speed. In order to realize the high accuracy measurement of wind speed of roadway from 0 m/s to 0.3 m/s and avoid the influence of the sensor installation angle on the measurement, this paper present a new method for applying the principle of ultrasonic time difference method to the measurement of wind speed in coal mine, introduced a new algorithm of precision measurement on ultrasonic transmission time. Furthermore, the structure of ultrasonic elevation and low power consumption was optimized.The results showed that this detection system achieves high precision measurement of wind speed from 0 m/s to 15.0 m/s in coal mine, it can meet the requirements of the coal mine better and has good economic benefit.