With the development of economy and the improvement of people's living standard, the civil demand for pneumatic tools is strong, and the market potential is huge. In this paper, air nail gun is taken as an example to make a simple analysis of its general working posture. Combined with the structure of human upper limbs and hands, it provides a reference basis for the structural design of the handle and a more reasonable scheme is obtained. Then, ANSYS Workbench is used for stress analysis of the hand part to further improve the handle modeling. At the same time, based on the design principles of hand tools, according to the results obtained from the analysis, combined with the anatomy of the hand, the design of the handle was improved and analyzed again. The results verify that the improved handle shape is more suitable for people to grasp, disperses the stress of the hand, distributes the stress more evenly in each area, and avoids the stress concentration.