An on-site test on envelope of a typical steel residential building in cold region is performed. The testing results provide evaluation bases for the energy-saving effects of the steel residential building. In order to evaluate the main factors that influence energy dissipation of the building and estimate the main energy dissipation positions, the heat transfer coefficient K of envelope and its actual energy consumption are calculated based on the testing data. The results indicate that the building envelope has good heat storage property and it could keep indoor thermal stability; the steel frames and windows have heat bridge effects. Through calculations of the energy consumption of envelope, it is showed that the tested building only meet the requirement of energy saving by 50%, instead of 65%; the external walls and windows are main energy dissipation parts. Finally the thermal design recommendations about steel residential buildings are proposed.