Hydraulic jack with safety valve

The invention relates to the technical field of hydraulic jacks, in particular to a hydraulic jack with a safety valve, which comprises an oil storage cylinder, a main cylinder and a pump cylinder, the oil storage cylinder, the main cylinder and the pump cylinder are communicated with one another, an oil pumping piston is arranged in the pump cylinder, a driving handle is arranged on the oil pumping piston, a working piston is arranged in the main cylinder, and a safety valve is arranged on the working piston. An oil filling hole is formed in the side wall surface of the oil storage cylinder, an oil plug is arranged in the oil filling hole, a pressure relief safety valve is arranged at the lower part of the oil storage cylinder, and the pressure relief safety valve is communicated with the main cylinder; one-way valves are arranged at the communication part of the pump cylinder and the main cylinder and the communication part of the pump cylinder and the oil storage cylinder; a maintaining device is arranged