Abstract: Aimed at the difficulties in the layout and demolding of plastic parts, a three-plate mold with a three-time core pulling mechanism was designed. For the layout of plastic parts in the mold cavity, the handle was arranged in the XY plane layout of the mold. Four types of mechanisms were designed for automatic demolding of plastic parts, which includes a angled-lift split core-pulling mechanism for stationary mold, a split core-pulling mechanism for movable mold, an angled-lift split three-time core-pulling mechanism for movable mold and a demolding mechanism with a sleeve ejector. For the design of angled-lift split three-time core-pulling mechanism, the first local core pulling was performed by driving the angled-lift split with inclined guide pillar. The second time-delay core pulling was conducted by driving an inclined ejector pin, an inclined angle lifter and an inclined ejector sleeve with the spring on the angled-lift split. The third time-delay core pulling was realized by means of the tie bar to lever set on the slider. The fractional core-pulling demolding was well performed by these mechanisms, which effectively ensured the quality of products during the plastic molding and automatic injection molding production processes, simplified the mould structure, and reduced the cost of the mold manufacturing. This design can bring a good reference for the design of the mold with a similar structure.