Impeller is the core component of centrifugal pump, and its rotating speed is higher than the force, and the blades on the impeller play a major role. The impeller must pass the static balance experiment before assembly. The inner and outer surfaces of the impeller should be smooth to reduce the friction loss of water flow. At present, there are four basic types of water pump impellers: runner type (single runner and double runner), vane type (closed and open), spiral centrifugal type and cyclone type. The performance structure of various impellers is detailed as follows. 1. Runner impeller: Runner impeller is a curved runner from the inlet to the outlet. This type of impeller is suitable for conveying liquids containing large particles of impurities or long fibers. 2. Vane impeller: The semi-open impeller and open impeller in the vane impeller are convenient for casting, maintenance and cleaning of impurities blocked during transportation. However, its disadvantages are: due to the wear of solid particles in the conveying process, the gap between the inner wall of the hydraulic cavity and the blades increases, which reduces the operating efficiency of the pump, and because of the increase of the gap, the stability of liquid flow in the flow channel is destroyed and the pump vibrates. This type of impeller is not easy to transport media containing large particles and long fibers. 3. Spiral centrifugal impeller: The spiral centrifugal impeller has twisted blades and extends axially from the suction port on the conical hub body. The delivered liquid will not touch any part of the pump when it flows through the blades, so it will not damage the pump. ? 4. Swirl impeller: Swirl impeller means that all or part of the impeller is retracted into the flow passage of the water pressure chamber, which has good anti-blocking performance. The flow of particles in the hydraulic chamber is driven by the vortex generated by the rotation of the impeller, and the movement of suspended particles itself does not generate energy, but exchanges energy with the liquid in the flow channel.