Abstract: To overcome the shortcomings of the traditional analysis method of supports in nuclear power plants in terms of quality and efficiency, the automatic identification algorithms of welding joints and loading joints of steel structure were solved, based on in-depth research on the topological and geometric characteristics of CAD models of various supports. CAD/CAE integration software with independent intellectual property was developed by PML（Programmable Macro Language）. It not only solved the problem of topological connectivity identification in the process of data exchange between CAD and CAE software and realized the pre-processing automation of CAE models of various supports in nuclear power plants, but also was successfully applied to a nuclear power project and obtained remarkable economic benefits.