Abstract: A self-priming jet pump includes a pump body provided with a water inlet and a water outlet. A jet tube and an impeller are arranged in the pump body. The jet tube is communicated with the water inlet and an inlet of an impeller. A first channel is arranged on the outer periphery of the jet tube. The first channel is communicated with the water inlet and the impeller. A cross-section of the first channel is a closed or open annular structure, and the first channel is around the outer periphery of the jet tube. The first channel is provided with a valve core. When a pressure at the water inlet is greater than a predetermined pressure at the impeller, the valve core moves to switch on the first channel. A cavitation problem is relieved by arranging the flow-increasing channel.