Abstract: Using the BeiDou observation data of 49 continuously operating reference stations in Shandong Province (SDCORS) in 2020, the atmospheric water vapor inversion was carried out using GAMIT software, and the annual hourly precipitable water vapor (PWV) series were obtained. Comparing the PWV obtained by inversion with the PWV observed by radiosonde weather station, the average deviation is 2.4 mm, the root mean square error is 3.4 mm, and the correlation coefficient reaches 0.98, indicating that the accuracy of inversion results meets the needs of meteorological research. The changes of PWV in the rainstorm process were analyzed from a single CORS station and the whole province. It was found that PWV began to rise 5 hours to 12 hours before the rainstorm. At the time of the rainstorm, the maximum value of PWV generally reached more than 60 mm, and the average change rate reached 1 to 3 mm/h. The closer the rainstorm occurred, the greater the change range of PWV. After the precipitation ended, PWV will decline rapidly. The change of PWV is highly correlated with the occurrence of rainstorm, which can be used for rainstorm warning research.