For being convenient for researching the dynamic characteristic and the improvement and use of small shaper, for improving the dynamic technical performance, the three-dimensional solid model of working mechanism was established with ADAMS. Each part of the model in ADAMS was set up. Simulation analysis on the working process of working mechanism was achieved. The structure optimization parameters of working mechanism were obtained. The result proves that the lengths of crank and rocker are almost no impact on the fluctuation range of ram speed. The location of revolute joint between rocker and frame has less impact on the return speed and acceleration of ram. The location of revolute joint between crank and slider impacts greater on the fluctuation range of ram speed.