Abstract: For complicated mountainous areas of Yunnan, A set of methods of fine grid (1km by 1km) annual precipitation (AP) distribution of were proposed by 2010 data. the principal component analysis was used to eliminate the high correlation of geographical and topographic factors, the K-means clustering was used to classify weather stations into different AP types, and naive Bayes classification was used to classify grids into different AP types by learning the classification characteristics of weather stations. the refined grid AP distribution of Yunnan in 2010 was obtained by regression equation and residual correction. the MRE of the fine distribution was only 0.17, and it can not only distinguish the AP type difference between the west and east of Ailao mountain as the windward slope and the leeward slope of the southwest warm and wet air, but also identify the rainy pattern in the western and southern edge of Yunnan.