Large injection molding, precision injection and thin wall injection are three main forms of injection molding. Different injection processes have different requirements for moulds. The characteristics of three different types of injection moulds were compared and analyzed, and the research status in various fields in China was summarized. With the rapid development of economy and the improvement of people's living standards, people in large-capacity washing machines, large-screen television, automobile, aerospace and other aspects of the development of higher and higher requirements, the corresponding large-scale injection molding. At present, the division of large injection molds has not yet formed a unified standard, generally considered that more than 3000 square centimeters of molds, can be called large injection molds. At the same time, there are more than 2 tons of mold quality is known as large injection mold. Compared with ordinary injection molding, large injection molding products are characterized by large volume and good quality. Large injection mold also has its own positioning, in mold design, mold material selection and other aspects have their own unique requirements, embodied in the following aspects: 1, cavity, strength, stiffness requirements. Due to the high pressure of the melt, the cavity of the large injection mold is easy to produce large deformation, and the elastic deformation increases with the increase of the cavity size and pressure. (2) cavity composition requirements. Compared with small and medium-sized injection molds, the cavity and core structure of large-scale injection molds are more complex. In order to improve the use efficiency and save raw materials, large-scale injection molds often use modular cavity structure, and the more complex cavity combination requires higher.