The traditional production line has a strong empirical dependence in the planning and design stage, timeconsuming in equipment joint adjustment, and difficult to visually show the real dynamic of the production line during production process. In order to solve the above problems, the brake disc flexible manufacturing production line was taken as the research object, integrated objectoriented technology, simulation modeling technology and modular technology, the digital twin model of the production line was established by using SolidWorks, CINEMA 4D, Unity 3D software and MySQL database to realize the manufacturing process simulation, process optimization, collision monitoring, robot trajectory optimization and virtualreal synchronization of the production line to solve the difficult problems in the early planning stage of the production line and save time of equipment commissioning phase, and improve the visual level of production line. The results show that through the virtual optimization and real-time simulation of the production line, the equipment utilization rate is effectively increased, the collision interference between the equipment is significantly reduced, the virtualreal synchronization deviation is within 800 ms, and the workshop management efficiency is effectively improved. The research results provide reference for other types of flexible manufacturing production lines construction.