The building is greatly affected by the fire, after the fire, the components will appear cracks, fall off, deformation, etc., the material performance, bearing capacity will be reduced, and even affect the overall safety of the structure. In order to do well the construction, maintenance and management of the engineering structure after the fire, it is necessary to test and appraise the engineering structure after the fire. Taking a high-rise residential building fire detection and identification as an example, this paper comprehensively evaluates the damage degree and influence range of structural components after fire through field investigation, material property detection and material microscopic analysis. The research shows that: In the detection and identification of buildings after fire, the grade of structural components should be initially assessed, and then the detailed identification and rating of components should be carried out in combination with various detection techniques to give the impact degree of fire on components, so as to facilitate the subsequent adoption of targeted reinforcement measures, in order to provide reference for the detection and identification of buildings after fire.