An efficient and convenient pneumatic device that meets the consistency requirements of batch product assembly is designed, involving the field of mechanical assembly fixtures and being applied to the three-point mechanical limit assembly of components. A new pneumatic device is designed based on a three claw pneumatic chuck using three dimensions modeling software. By designing the assembly dimensions of the overall structure of the component, precise positioning in the Z-axis direction of the space between the two components can be achieved, while a three-point uniformly distributed limiting assembly mode is achieved. Through the centripetal movement of the three claws of the pneumatic chuck, the three-point clamping deformation of the thin-walled cylindrical shell is achieved, the mechanical limit and assembly between the internal components of the shell is completed. And the kinematic and dynamic simulation analysis of the internal transmission mechanism of the pneumatic system is completed through simulation software.