A self-priming starting device for a centrifugal pump is mounted on a water inlet pipe of the centrifugal pump and includes an outer housing, an inner housing, a primary spacer, a secondary spacer, an opening and closing disc and a tertiary spacer which are sequentially provided in the outer housing from top to bottom, and an elastic steel plate provided in the water inlet pipe. A drum is provided in the inner housing, and air inlet pipes and air discharging pipes are provided on the inner housing. The drum is provided with drum chambers and a three-blade support is provided in the drum. The opening and closing disc is provided with a vertical rod. A gas-liquid cutter is provided between the primary spacer and the secondary spacer. The primary spacer, the secondary spacer, the opening and closing disc and the tertiary spacer are provided with through-holes.