Plastic industry is one of active industry, plastic products are always made by mould. Injection molding is used widly and is one of the most prospect formating mothed in today market. According to search for various kinds of materials,and paying close attention to injection mould the state of development through the inquiry and network , finally confirm to design the Lubao car ashtray lid of two shape injection mould,and then provide the whole design plan . First plastic product analysis is conducted, including its material and shape size and so on. Then the number of the cavity and the choice of injection machine, as well as the general mold concrete design, include the face designing of the injecting system,cavity and core design and the choice of formate port mechanism.The last and the most important part is the detail design of injection mould , include formate port design , noting system ,cooling system, air supplement and platoon overflows system, the outing organizations, the organization for taking out the core and so on.