Abstract: Based on a relationship between monthly precipitation anomaly and monthly circulation, the forecast equation coefficients are calculated as variables. The sample data are selected from which has similar potential height field to that in the forecast month. The monthly rainfall forecasts is improved by calculating the equation coefficients. The latest seven-year hindcast tests proves that the method of calculating of coefficients has certain value in operational application. Under the consideration of a limited accuracy of T63/NCC monthly dynamical extended-range forecast products (T63/NCC MDERFP). Also, results are obtained in the application of monthly rainfall forecast of Anhui Province by T63/NCC MDERFP。