In this paper, the 0-36 h downward shortwave flux at ground surface (SWDOWN) forecasting has been simulated by WRFV3 continuously for approximately four months: January, April, August and October in 2009. The hourly total solar radiation (HTSR) forecasting was converted by the 12-36 h SWDOWN output from WRF simulation. And HTSR forecast was compared with the observation of Wuhan Station. The results show that: （1) the simulation of HTSR is interrelated well with observation. Correlation of every month is larger than 0.8 and corresponds to 0.01 significance levels. （2) Each time HTSR mean forecast errors (MFE) in the morning and evening are smaller than in other time, but the maxima of mean absolute percentage errors (MAPE) appear in the morning and evening. MAPEs from 9 AM to 3 PM change a little and their reliability is higher than in other time. （3) WRFV3 model has ability to forecast the total solar radiation in clear, cloudy or overcast weather conditions, especially good performance in clear sky. However, this simulation is not a perfect initial field for power prediction of photovoltaic systems. Our future work is to use some methods for correcting HTSR forecast and improve their practical application.