Abstract:Based on data of three GNSS observation stations in Shaanxi from January to June in 2018, the water vapor inversion is carried out by using Beidou satellite navigation system. We use different ephemeris products to calculate the water vapor, and compare them with the results calculated by IGF and radiosonde data. At the same time, we compare the water vapor results obtained by different ephemeris with each other. The results show that the three ephemeris can obtain high-precision and high-reliability water vapor results. The accuracy of water vapor inversion with precision ephemeris and fast ephemeris are equivalent, the deviation of each station is better than 1 mm, the standard deviation and root mean square error are better than 3.5 mm. The ultra-fast ephemeris (forecast part) is used to invert water vapor at each station with a deviation of about 1 mm, the standard deviation and root mean square error are better than 5 mm. Combining the corresponding accuracy of water vapor inversion of three products, it can be obtained that the three ephemeris products can invert precipitable water vapor and the water vapor value calculated by the ultra-fast ephemeris (forecast part) can provide a reference for weather forecast.