Abstract: According to the topographic and climatic characteristics and long-sequence precipitation data of the Changbai Mountain,the distributive charcteristics of coefficients of relative precipitationin in different slope directions of the main ridges in a year and from May to September are analyzed,and the relation functions between relative precipitation and slope direction angles are established.The order of precipitation in different slope directionsins on various ridges is SW & gt;S & gt;W & gt;N & gt;E & gt;NE,their corresponding relative Precipitation coefficients are 1.083,1.071,1.060,0.917,0.913,0.912 in a year,and 1.071, 1.059,1.050,0.933,0.933,0.922 from May to September.The precipitation is highest in windward slopes and lowest in leeward slopes,and the former is 20.5%more than the latter.The effect of slope is great in the Panling, Weihuling Yingerling ridges and Dunhua basin.The effect of slope on precipitation depends on the interception of slope to air current.