Focusing on the difference of solar radiation in different regions and topographical conditions, an hourly calculation model of solar radiation at arbitrary direction and inclination angle is established. Using the solar radiation model, the total radiation of 1951-2018 in Yongding River Basin is calculated, and its hourly variation characteristics at arbitrary inclination and direction angles are analyzed. The results show that the annual solar radiation decreased in the Yongding river basin from 1951 to 2018. The changing pattern of daily solar radiation is similar at any inclination angle with a parabolic pattern, and the peak value is mainly affected by geographical latitude and altitude. The distribution of solar radiation is symmetrical and decreasing along the east and west directions at arbitrary slope azimuth, taking the center of the basin. Obvious monthly variations at arbitrary inclination azimuth is shown in the solar radiation which has larger fluctuation in the period of January to March and October to December than in April to September. This paper can provide basic reference for quantifying energy budget, utilizing solar energy and analyzing evaporation process in land surface.