The JT1401 air velocity sensor is developed based on the basic principle that the high-sensitivity thermistor loaded with current has a corresponding functional relationship with the wind speed. The sensor has the characteristics of omnidirectional test and fast response time, and can quickly capture the dynamic changes of tiny air flow, and can test the wind speed as low as 0.05m/s, which is suitable for the test scene of slight wind speed in the environment, especially the building microclimate environment test.