Precipitation, as one of the most important basic indication for hydrologic prognosis and water resources distribution, requires interpolation in measurement of precipitation. This paper, on the basis of multiple regression, forms two or more regression equations between two rainfall stations, and it will solve coefficients to the regression equations by least square method. The author studies Qinshan Reservoir rainfall station in Muyang Stream watershed of Fujian Province, by referring to reservoirs adjacent to it and provides resolves of regression equations for multiple rainfall stations. In compare of significance test between the stations, the author selects the the repression equation with the lease mean square error and applies it to interpolation of precipitation. The test result of this article offers reference to engineering practices.