A self-priming pump is a type of fluid pump that can start the pumping process without the need for external priming. This means that it can evacuate air from the suction line and create a partial vacuum to discharge water while also evacuating any air. Self-priming pumps are necessary if a pump has to be placed above the level of liquid, allowing air into the line, which can lead to challenges such as overheating and pump failure.

The design of a self-priming pump provides an opportunity for the constant presence of fluid in the pump body, which enables the pump to better handle air pockets or accumulations of air bubbles in the pumps operating mechanism that can impair its proper operation. In practice, self-priming pumps are previously filled with the relevant fluid through a small port located on the pump body (the chamber where the impeller is located). After this operation, the pump can be operated, triggering turbulence that allows the fluid to rise and "clear" the piping of air.

Positive displacement pumps, including rotary gear pumps, lobe pumps, vane pumps, and diaphragm pumps, are self-priming in principle. When the pump is shut off, the design of the priming chamber (normally involving a goose-neck on the suction piping) ensures that enough liquid is retained so that the pump can self-prime on the next occasion it is used.

Self-priming pumps are used in various industrial and commercial facilities, from steel mills, power plants, and sewage treatment facilities to wineries, breweries, and more.