Welded structure is usually used in current nailing machines. When a nailing machine was used for a period of time, the base of the machine was deformed, so products produced with the machines become waste. The reason for these problems is that the design of window shape around the body column plate is unreasonable, so the plate often cracks. In addition, the hydraulic system in current nailing machines is unreasonable too, which makes production less efficient. Aiming the current problems of the nailing machine, finite element analysis software ANSYS is used to analysis and find the machine’s stress concentration areas. According to the analysis results, the shape and size of these areas are re-designed, which has the minimum area stress and deformation. The welded machine body is changed into a casted one, and the other modules are also re-build, all of which make the machine has longer service life. Through the process analysis, the hydraulic system is re-designed too, which improves the equipment productivity greatly.