In the product development process, manufacturing flexibility requirements continue to increase, and with the emergence and development of digital twin technology, virtual scenes can be created to observe, analyze, and predict data. Compared with traditional models, the risk is lower and the investment cost is lower. The slush molding process is one of the important processes in the production of automotive interiors, and the difficulty of improving the process is particularly prominent. Based on the Tecnomatix Plant Simulation software, this paper digitally designed the slush molding process, built the corresponding simulation model and logic program, and carried out the production scheduling simulation according to the production work order; then used the simulation experiment method to optimize the process parameters, and after comparing the simulated production capacity data with the actual production capacity, the accuracy of the model is verified, and finally, the production capacity prediction under different production requirements can be realized, which can effectively reduce the cost of process improvement.