The invention discloses a CAD (computer-aided design)/CAE (computer-aided engineering) integration method and a CAD/CAE integration system for a steel support structure of a nuclear power plant. The CAD/CAE integration system comprises a CAD system, a CAD/CAE integration tool and a CAE system, wherein the CAD system is used for generating a CAD model of a steel support structure, the CAD/CAE integration tool is used for searching CAD model data and converting the CAD model data into a command stream recognized by the CAE system, and the CAE system is used for receiving the command stream, reconstructing a CAE finite element model of the steel support structure according to the command stream and outputting the CAE finite element model. The CAD/CAE integration method and the CAD/CAE integration system have the advantages that the method and the system are capable of performing topological transformation on the CAD model by extracting key characteristic information in the CAD model, automatically generating a data format recognizable by CAE software and reconstructing the finite element model in the CAE software quickly finally; the CAD/CAE integration tool of the steel support structure is developed by the PML, so that zero-distortion conversion of the CAD/CAE model is achieved truly.