Reservoir water level (RWL) data are crucial for water resource management but are often inaccessible due to data sharing barriers. Although ICESat-2 laser altimetry offers high-precision observations, its applicability in China"s complex environments remains under-assessed.Using ICESat-2 ATL13 data (Oct 2018–Dec 2023),this study retrieved RWL series for 847 Chinese reservoirs via the Normalized Median Absolute Deviation (NMAD) method,systematically analyzing accuracy,coverage,seasonal amplitudes,and trends.Validation against in-situ data from 93 reservoirs showed high accuracy(MAE=0.126m,R=0.978,RMSE=0.164m),with robust performance even for small reservoirs (<1km2) .Analysis of RWL anomalies across seven major river basins revealed strong correlations with hydro-meteorological events (e.g.,abrupt drought-flood alternations,typhoons),confirming ICESat-2"s viability for monitoring extreme regimes and regulation responses.Seasonal amplitudes exhibited significant spatial heterogeneity west,low-east"),peaking in the Southwest Rivers (22.40m) and Yangtze River Basin (19.63m) Nationwide,RWLs showed an overall downward trend (-0.228m/a).Spatially,a "rising-east,falling-west" pattern emerged: significant declines occurred in the Southwest and Yangtze basins,while rising trends were observed in the Pearl,Hai,and Liao River basins.This study validates ICESat-2"s potential for monitoring RWL changes across China,providing a scientific basis for regional water management.