In order to study thermal insulation performance of the metal venetian blind for shading， the solar heat gain coefficient of 3mm clear glass、the shading coefficient of metal venetian blind for shading and inner-outside surface temperature of the 3mm clear glass under different conditions are tested and analyzed by the shading coefficient test platform that is based on solar-simulated light source. The results show that the metal venetian blind for shading holds about 87% of heat from the solar radiation when the metal venetian blind is closed， and the metal venetian blind for shading holds about 43% of heat from the solar radiation when the metal venetian blind is levelled. The analytical results have guiding-significance for thermal insulation evaluation of the metal venetian blind for shading.