The invention discloses an oil gas pressurization device which comprises a gravity separator, a cyclone separator and a screw rod pressurization machine. The cyclone separator comprises an upper cyclone separating cavity and a lower liquid storage cavity, and the upper cyclone separating cavity and the lower liquid storage cavity communicate with each other through a liquid outlet pipeline; a liquid outlet of the lower portion of the gravity separator communicates with the lower liquid storage cavity through a pipeline; a gas outlet of the upper portion of the gravity separator communicates with a gas inlet of the upper cyclone separating cavity through a pipeline; a gas outlet of the upper cyclone separating cavity communicates with a gas inlet of the screw rod pressurization machine through a pipeline; a gas outlet of the screw rod pressurization machine is provided with a gas conveying pipeline; the gas conveying pipeline communicates with a gas exhaust pipe and a high-pressure gas return pipe correspondingly; the tail end of the high-pressure gas return pipe communicates with the upper portion of the lower liquid storage cavity; the lower portion of the lower liquid storage cavity is provided with a high-pressure liquid draining pipe; and the tail end of the high-pressure liquid draining pipe communicates with the gas exhaust pipe. The oil gas pressurization device can realize gas-liquid-mixed pressurization conveying.