自吸油泵启动前先在泵壳内灌满水（或泵壳内自身存有水）。启动后叶轮高速旋转使叶轮槽道中的水流向涡壳，这时入口形成真空，使进水逆止门打开，吸入管内的空气进入泵内，并经叶轮槽道到达外缘。然后与右回水孔流来的水汇合，顺着蜗壳流动。由于液体在蜗壳内不断冲击叶栅，就同空气强烈搅拌混合，生成气水混合物，并不断地流动致使气水不能分离。混合物在蜗壳出口被隔舌剥离，沿短管进入分离室。在分离室内空气被分离出来，由出口管排掉，而水仍经左右回水孔流向叶轮外缘，并与吸入管空气相混合。如此反复循环，逐渐将吸入管路中的空气排尽，使水进入泵内，完成自吸过程。
Before starting the self-priming pump, fill the pump housing with water (or there is water in the pump housing). After startup, the impeller rotates at a high speed so that the water in the impeller channel flows to the volute. At this time, a vacuum is formed at the inlet, so that the check valve of the water inlet is opened, and the air in the suction pipe enters the pump and reaches the outer edge through the impeller channel. Then it joins with the water from the right return hole and flows along the volute. As the liquid continuously impacts the cascade in the volute, it is strongly stirred and mixed with the air to form a mixture of gas and water, and the continuous flow makes the separation of gas and water impossible. The mixture is separated by a tongue at the outlet of the volute and enters the separation chamber along the short pipe. The air in the separation chamber is separated and discharged by the outlet pipe, while the water still flows to the outer edge of the impeller through the left and right return holes, and is mixed with the air in the suction pipe. Such repeated circulation will gradually exhaust the air in the suction pipeline, so that the water will enter the pump and complete the self-priming process.