Abstract: The ground-based GNSS remote sensing water vapor detection got high spatial and temporal resolution atmospheric water vapor data by acquisition signal of satellite navigation system, made up the shortage of conventional sounding in space and time, which had important application value to the weather forecasting, climate research and artificial influence on weather.This paper used BeiDou experimental network data, combined with the radiosonde observation, made detailed comparative analysis among BeiDou, GPS and sounding system, gave the preliminary results of performance and accuracy of BeiDou vapor detection.The result of PWV were consistent detected by BeiDou, GPS and radiosonde, which well reflected the change regularity of PWV. PWV detected by BeiDou was more than that of GPS, there was a system error of 2-3.3 mm between the two systems. The two systems were more consistent when the PWV relatively lower. There were systematic errors and standard deviation between the water vapor detection by BeiDou and radiosonde. Positioning and orbit determination model need to be optimized. The stability of the system need to be improved.