Abstract: Based on the SketchUp,a calculation model for enclosed space’s solar radiation is established. Instant shadow images of the enclosed buildings model is exported from the SketchUp through the Ruby. According to the characteristics of these shadow images formed by the enclosed space buildings,a pixel-based HIS color space building shadow detection algorithm is proposed to distinguish and quantify the occluded part of the enclosed space building facade;then the traditional short wave radiation calculation method is adopted to estimate the short wave radiation intensity of a building facade in the enclosed space. The verification of the model was done by using the measured data obtained by testing in some cities,proving that the model is suitable for the calculation of solar radiation on the building facade in the enclosed space,which provides a more convenient and quick calculation method for architectural designers to accurately estimate the solar radiation intensity of the building facade in the urban enclosed space when it comes to designing and planning urban buildings.