The paper investigates current coupling scheme of physics and dynamics of the numerical prediction model. The Wedi (1999) coupling scheme of physics and dynamics is introduced into the Global/Regional Assimilation and Prediction System (GRAPES). The impact of two-time-level physics is implemented in the Wedi scheme, i.e. the physics contribution at the departure point together with the arrival point give feedback to the dynamic core of the model. So the Wedi scheme is the second-order accurate coupling scheme and is more reasonable and precise than the old one-time-level scheme in the GRAPES in theory. The consecutive numerical experiments are performed by using of the Wedi and old coupling scheme in the GRAPES model. Results show that the Threat scores of precipitation forecasting with the Wedi and old coupling scheme is tinily different, the forecasted precipitation may have a little variation but it cannot change the magnitude. Based on the analysis of the averages, it is found that the Wedi scheme has a positive impact on precipitation forecasting skill score, that is to say, the Wedi coupling scheme improves the GRAPES model and has a positive effect on enhancing the precision of precipitation forecasting.