Abstract: Multivariate nonlinear regression model was established to simulate the solar radiation on level surface of 1 km grid-cells in China. The validation shows the prediction accuracy is 96.63 percent. Based on digital elevation model (DEM), the direct radiation ratios of slope to level and the sky view factors of slope were calculated respectively to modify direct and diffuse solar radiation which aimed to get the actual solar radiation on 1 km ground surfaces. The results indicated that great difference of solar radiation between slope and level surfaces existed in hill and mountainous regions, and the maximum difference might reach 67 percent in China. The simulated radiation could be used in extensive fields of agricultural practices and researches, such as assessment of agricultural potential productivity, agricultural zoning, distribution of crops, and returning farmland into forest and grassland.