Abstract: To realize the rapid energy consumption assessment of the product in the 3D design software, rough machining and finish machining energy modeling was put forward based on the construction of design feature-machining feature-processing method database, and the mapping relation of design feature and machining feature was built. It is proposed that the rapid processing energy consumption was realized by marking feature surface, defining feature types and inputting feature accuracy level based on the UG/Open API. The function of rapid energy consumption assessment was realized by compiling.dll format dynamic database using C++ language and invoking dynamic database in the CAD modules. The space product was taken for example to verify the feasibility of the project.