A pressure vessel fatigue test system belongs to pressure vessel test technical field, comprising oil circuit pressure device, pressurizer, weight relieving motion, and measuring and control system. The oil circuit pressure device, pressurizer, weight relieving motion consists of pump linked by pipeline and oil pump driven by electric machinery, solenoid valve, overflow valve, water cooled oil cooler, back oil filtration device, oil tank and pipelines linked with them, the measuring and control system is consisted of electric contact pressure gauge, temperature sensor, pressure sensor, computer, controller for measurement and control temperature of pressure vessel, hydraulic oil, one-way throttle valve and high pressure filtration device are fitted with pipeline linked with solenoid valve and the container, stabilization tank is fitted with oil return pipe linked to solenoid valve and oil tank. The invention is suitable for fatigue test of pressure vessel containing impurity within and fairly high pressure needed and reconstruction to present pressure vessel fatigue test device.