Prefabricated buildings have the advantages of good component quality, fast construction speed and less construction waste, which is an important measure to implement ecological civilization, save resources, protect the environment and reduce pollution. The composite structure of section steel and concrete gives full play to the advantages of light weight, high strength, assembling construction and high recovery rate of steel. However, the construction method of assembly is still in the research stage. In order to explore the key problems in engineering application, such as mechanical performance, material behavior, failure phenomenon, connection design etc. of SRC beam-CFST column composite frame (hereinafter referred to as “composite frame”). On the basis of the experimental results of exterior joints in the early stage, the whole process mechanical behavior of composite frames under vertical load and horizontal low cyclic load is studied by using ABAQUS finite element analysis software. The research shows that the assembled connection mode has better static and seismic performance, and the material performance is fully utilized. The mechanical performance of the full welded and bolt-welded hybrid connection is similar. Increasing the thickness of the ring plate and the height of the beam section can improve the bearing capacity and energy dissipation capacity.