Based on the dynamical extended range forecast products from 1983 to 2005, the forecast experiment on the interpretation and application of monthly dynamical extended range forecast products was carried out. The results show that the method has better prediction capability for monthly precipitation forecasting in Shaanxi Province, which is located on the northeast side of the Tibetan Plateau. The PS score is higher in summer and autumn and lower in winter and spring; meanwhile, it is unstable during the period of seasonal transition of atmospheric circulation.