Along with our country economy fast development, the building and renovation is becoming more and more widely, layer for steel structure system, relying on its obvious advantages, has gradually become one of hot topics in the study of engineering. Combining with engineering example, through the integrity research, bearing capacity calculation, field exploration, the analysis of the concrete strength testing, etc., has carried on the appraisal on the safety of building structure, and analyses the feasibility of after add layer. In layer for steel structure design, at the same time puts forward the design and construction of some key points, provide a reference for similar projects.