Years’ precipitation data of Chongqing from 101 metrological stations has been adopted in the paper and the regression equations between annual precipitation and altitude, longitude, and height have been obtained by the use of SPSS, then elaborate simulation of Chongqing’s precipitation resources based on regression analysis was completed through the 1km×1km grid system and fitted equation. Elaborated simulation of precipitation resources was realized by best spatial interpolation method with the support of GIS; then the results of two different simulation methods were coupled in the form of linear combination to obtain the coupling simulation of spatial distribution of Chongqing’s precipitation resources, finally the precipitation resources were summed up and distributed according to different administration areas at county level and thus obtain precise simulation data of precipitation resources in each county of Chongqing. The results showed that there is a remarkable regional difference in the spatial distribution of precipitation resources of Chongqing, and it decreases from the southeast to the northwest in general, with the annual precipitation higher than 1270mm in southeast and lower than 1080mm in northwest.