Overload protector is equipped in press machine to check the hydraulic pressure of cylinder inside the slider. If happened overload, the hydraulic pressure of cylinder will be released immediately within 3/1000 seconds. When happen overload, in order to protect the press and die, the press will stop working immediately after receiving the signal from limit switch. After happen overload, the air will drive hydraulic pump to supplement normal working pressure immediately and the press can work normally. Has pressure control valve inside of overload protector. Can be adjusted automatically and eliminate the impact of rising pressure.