Water level information is an important parameter for studying changes in the water cycle, even the climate and ecological environments.It is of great significance to monitor the water level changes in near real-time and with high precision.However, traditional water level gauge is a relative water level measurement approach in a small range and has a high cost.The Global Navigation Satellite System Interferometric Reflectometry (GNSS-IR) uses the Signal-to-Noise Ratio (SNR) data from the GNSS receiver installed on the coast to estimate the water level change, which provides a new monitoring approach for water level measurement with high accuracy and near real-time.Here, 30 days of GPS, BDS and GLONASS SNR data from a multi-GNSS station at Badong station in the upper reaches of the Yangtze River are used to estimate the water level changes, which are then compared with the in-suit water level station observations.The results show that GNSS-IR obtains centimeter-level water level results with the minimum RMSE of 6.43 cm.The estimation results of GPS and GLONASS system at L1 frequency and BDS system at B1 frequency are better, and the accuracy of GLONASS L2 frequency is lower than that of other frequencies.The joint multi-GNSS system improves the time resolution of GNSS-IR estimation of water level changes.