Abstract: In order to improve automation of RPV nozzle safe end weld γ-Ray inspection device, a control system was designed and manufactured. The RPV nozzle safe end weld automatic γ-Ray inspection device was based on MCU to implement inflating and deflating of the air bag, air cylinder feed control and the pressure control of the air bag. Hall sensors were used to position weld and CCD camera to display real time movement of the system. Test results show that the automatic control system of under water γ-Ray inspection is stable and position accuracy meets the requirements.