Based on UG10.0 software as the secondary development platform, the UG/MenuScript and UG/KF (knowledge fusion) language are used in this paper to develop a computer-aided design system for casting process (CAD-CP). The CAD-CP system is divided into five parts: information acquisition module, riser design module, runner design module, sprue cup design module, and subsidized design module. To test the effectiveness of the designed system, a typical disk part of flywheel casting process is investigated by the CAD-CP system, where the process structures are designed and the process parameters are obtained. Besides, the numerical simulation of flywheel casting by ProCAST software and experiment are carried out, and the results show that the experiment is consistent with the numerical simulation. It indicates that the as-designed CAD-CP system would meet the standard of the casting process, where the design workload of the casting process is reduced effectively as well as the design efficiency is improved.