Abstract: The technology of resizing chromium plating on the inner cylinders of aircraft piston rods was studied. The key points and difficulties of parts features, tooling design, chromium plating process optimization analysis were analyzed and explained. A set of tool was designed for resizing chromium plating of the piston rods, and the correct chromium plating parameters were confirmed to match the designed tool through the experiment. The inner cylinders of the piston rods were resized through the tool with these parameters. The results show that the designed tool and plating process parameters were well matched, and the size of the inner cylinders of aircraft piston rods could meet the requirement after resizing; the surface of the plating layer was uniform and smooth, and the piston rods could be used for aircrafts again.