Abstract: The factory inspection of metal parts before the installation of thermal power units during the construction period is to supervise the manufacturing quality of the metal equipment under supervision, find out the quality problems existing in the manufacturing stage of the equipment, and prevent the defects from being brought into the operation stage of the equipment, so as to eliminate the potential safety hazards of the unit in the operation stage to the greatest extent. The problems of boiler steel structure, heating surface tube panel, header and boiler pipe found in the pre-installation inspection of thermal power units are analyzed. The results can provide useful reference for the factory inspection of metal parts before installation of thermal power units in detection methods and key detection parts.