In order to study the characteristics of spatial distribution of precipitation in Lu'an, the paper used Kriging interpolation method based on ArcGIS, and mainly to dispose the daily precipitation data in recent 56 years of lu'an.Then it got the rainfall spatial distribution and analyzed the spatial distribution characteristic of all seasons, average annual precipitation and flood season precipitation. The results show that the precipitation difference of autumn and winter in Lu'an is unobvious.The spring precipitation gradually reduces from south to north nd from west to east because of the influence of latitude and terrain. In summer, the precipitation is mainly influenced by terrain drops sharply from southwest to northeast. In southwest mountainous area, the precipitation is up to 600mm;the spatial distribution of annual precipitation reduces from southwest to northeast. The closer to the Dabie mountain hinterland, the greater the rainfall is.The most precipitation reaches 1370 mm,the difference is 470mm. But in the mountains and plains belt,the falling gradient is low;the spatial distribution of precipitation in flood season also reduces from southwest to northeast, but the precipitation concentration efficiency reduces from west to east in south area, which reduces to 0.56 and then jumps to 0.67 in northern region. The result indicated that the inner-year variation of precipitation is great because of the influence of speed and time of terrain and rain belt.