The work aims to design a dynamic distribution method for important materials at key stations in order to reduce the cost of material distribution and inventory management on the line of assembly workshop and improve the adaptability of distribution link to the change of production tempo. Firstly, the K-means algorithm was adopted to conduct a preliminary classification according to material value, packaging volume and universality, and the important materials at key stations were determined in combination with the coefficient of variation of demand. Secondly, the material distribution method based on dynamic distribution time and quantity was designed according to the characteristics of engine assembly line, and the total distribution cost model including transportation cost and line inventory cost was established. Finally, the production logistics simulation model was built through Flexsim software to simulate the existing distribution method and the designed method in Z workshop respectively for comparative verification. After the implementation of dynamic distribution, the average inventory capacity and holding inventory cost of important materials were effectively reduced, with the maximum decrease of 23.91% and 23.96% respectively. The proposed method can improve the pertinence of workshop material management, reduce the total distribution cost and improve the flexibility of distribution system.