Abstract: An optimal design method for cutting at an impeller inlet provides a parameter selection and an optimal method for cutting lengths of a vertical side and a horizontal side, of the inlet, a diameter of the inclined position of the front and rear cover plates, the wall thickness ?1 of the front cover plate and the rear cover plate at an exit of the impeller after the inclination optimization, the number and wrap angle ? of the long blades after optimization, an inlet diameter Dsi, arc length, axial offset degree, inclination angle, and the thickness of the splitter blades. The method is simple in implementation and can effectively improve the performance of the jet-type self-priming centrifugal pumps.