The main purpose of this work was to develop a mathematical model and computer programs for design analysis in composite core-pulling mechanism. The injection mould with slanted guide pillar for two-step core-pulling from the side of the product effects significantly the quality and efficiency of plastic part. The study is a one-dimensional analysis of secondary-ejector mechanism, based on a forward marching technique of solution for the simple structure and high safety and reliability. Using the simulation analysis of mechanical system based on Pro/E, the mechanism can solve the problem that ...