According to the complex motion of fiveaxis computer numberical control (CNC) machine tools, the factors that affect the machining accuracy of parts are numerous. An error model of the technology system was established by using multibody system dynamics, which took multiple factors into account to analyze the machining accuracy of parts at each stage of the system links by the comprehensive error model. The machining accuracy of parts was predicted before the machining. Cutting experiment was used to verify the accuracy and effectiveness of the model. The effectiveness and accuracy of the error model are confirmed by the experiment of cutting tests on parts based on the math model of multibody system dynamics, and the model lays a solid foundation for further research and error compensation.