Abstract: Average precipitation is the most commonly used and important index in the sectors such as water and meteorology. The repeated construction of rainfall stations in different sectors causes a waste of resources,the data standards among different sectors are not unified, and the sharing mechanism has not been established. The calculation methods among different sectors and within different departments in the same sector are inconsistent. In order to solve the problem of inconsistent calculation of average precipitation, realize rapid data query and serve different objectives, this paper proposes a solution of combining arithmetic average and area weighted, which is calculated into the result database by system. This method is fast, efficient and easy to maintain, and the results can be used as the data source for later analysis of multi-year mean value. Further optimization of the algorithm in the future stage can realize resource optimization and avoid duplicate construction.