Abstract: Water vapor is an important factor affecting weather changes, and the occurrence of disaster weather is often accompanied by sharp changes in water vapor content and spatial distribution. In response to the relatively limited research on the inversion of atmospheric precipitable water vapor (PWV) using the ground-based BeiDou system(BDS), this article further verifies the accuracy of BDS PWV inversion and the relationship between PWV and actual precipitation. A localized atmospheric weighted mean temperature (T^m) model was constructed using data from sounding stations and adjacent stations of the Continuous Operating Reference Station (CORS) in Hunan province. Based on this model, water vapor inversion was carried out to analyze the accuracy of BDS water vapor detection and explore the response relationship between PWV and precipitation by combining with actual precipitation. The results showed that the BDS PWV calculated by CORS stations is provided with a strong correlation in compared with sounding data, with root mean square error and average absolute error of both within 4 mm. The inversion results meet the requirements of water vapor monitoring. There is a clear connection between PWV and actual precipitation. The rapid accumulation of water vapor 6 h to 12 h before precipitation provides sufficient conditions for precipitation to occur, and PWV of 60 mm can be used as a threshold for precipitation forecasting. Therefore, continuous monitoring of water vapor using the BeiDou system can play an important role in monitoring and predicting precipitation, water and drought disasters.