Abstract: The western edge of the Hengduan Mountain (WHDM) is one of the regions where the rainy season starts the earliest in China and the spring precipitation amount in some stations even surpassing summer precipitation. Using high density station rainfall data and the European Centre for Medium-Range Weather Forecasts fifth generation reanalysis products (ERA5), the detailed range of spring precipitation over the WHDM is analyzed in this paper and the possible causes of regional differences in spring precipitation are discussed. The typical spring precipitation region over the WHDM locates in the Nujiang River Valley in Yunnan province between 26.57°N-27.8°N. In this region, the rainy season starts from the 9th pentad (mid-February). The rainy season can last for over to eight months, with the highest proportion of spring precipitation in the whole year. And the annual precipitation peak occurs before April. The rainy seasons start before April both in the eastern region (E) and the southern region (S), which are adjacent to the region W of spring rain stations. However, annual rainfall there are dominated by summer precipitation. Further analysis shows that the precipitation difference between region E and typical spring rain region W may be affected by the dynamic background difference caused by topography and westerly in early spring, and also by the difference of water vapor condition caused by the difference of southerly in late spring. The difference of precipitation between region S and typical spring rain region W may be mainly affected by the different water vapor conditions caused by the difference of meridional winds, and the difference of vertical uplift motion under the action of local topography may also have an important contribution.