Compared with traditional single-layer moulds, multi-layers injection moulds can get two or four times of production but no necessary to add extra equipments or machines, thus greatly reduced cost. This kind of mould can be fixed in similar injecton machine that for simple-layer moulds, and the working speed only a little slower than single-layer moulds, clamping forces just added 10%-15%, but production efficiency increases several times more than traditional single-layer moulds.