The invention discloses a hydraulic oil piston type natural gas sub-station compressor, which comprises a high-pressure oil pump (1), a pressure control valve (2), a pressure oil tank (3), a hydraulic reverse valve (4), a flow sensor (5), a bridge type valve bank (6), a gas compression cylinder tank group, a pressure sensor (9), a pressure relay (10), a high pressure gas storage cylinder (11), an automatic control system (12) and the like. The hydraulic oil piston type natural gas sub-station compressor can be abutted with a general natural gas transportation tanker without using a mechanical piston or a gas cylinder; and pressurized compression of natural gas is finished by using a circulating manner that pressure energy for air inlet of the natural gas and driving kinetic energy of a hydraulic system are alternatively subjected to air inlet, compression, high-pressure exhaust and switch in the gas compression tank. The natural gas sub-station compressor has the advantages of energy saving, environment friendliness, no friction, leakage or noise, slowness in temperature rise, high work efficiency and the like.