Solar radiation is an important factor effecting indoor thermal environment. External decorative materials of buildings have different properties in absorbing, reflecting and re-radiating the solar radiation because of their different color, texture and degree of roughness. In this paper, based on the establishment of thermal gain or loss model of architectural enveloping structure, we analyzes the influence of solar radiation of different external decorative materials on energy-saving of buildings by theoretic analysis and calculation, which provides the reference for the selection of external decorative materials in architectural design.