The invention provides a gas-liquid mixed self-suction type centrifugal pump. A pump body with axial liquid returning is adopted. After the pump is started, a impeller rotates, the liquid stored in asuction chamber and the air in a suction pipeline are added together and are completely mixed in the impeller, under the action of centrifugal force, the pressure of a front end is reduced, a flap valve is opened by the impact force of water, the liquid enters, and meanwhile, the liquid in the impeller is entrained with gas to flow towards the outer edge of a volute chamber, a white foam belt witha certain thickness and an adjustable rotating liquid ring are formed on the outer edge of the impeller, the gas-liquid mixed body enters a gas-liquid separating chamber through the pump body, and atthe moment, due to the fact that the liquid velocity is suddenly reduced, lighter gas is separated from the mixed solution, the gas is continuously discharged upwards through a discharging outlet ofthe pump body, and the degassed liquid returns to a liquid storing chamber, and enters the impeller again through a liquid returning hole, and then is mixed with the gas sucked in the suction pipelinefrom the inside of the impeller again, and flows to the outer edge of the impeller under the action of the impeller rotating at a high speed. The process runs in cycle, the self-suction process is completed until the gas is completely sucked up.