The invention discloses a single-action constant flow paddle pump. The single-action constant flow paddle pump comprises a pump body; a front pump body cover and a rear pump body cover are arranged on the front side and the rear side of the pump body correspondingly; a pump shaft is arranged on the front pump body cover and the pump body in a penetrating mode, and the pump shaft and the pump body are arranged in an eccentric mode; the circumferential direction of the pump shaft is provided with a plurality of pump shaft grooves, each pump shaft groove is internally provided with a blade, the other end of each blade is connected to a blade rotating groove, and the blade rotating groove and the pump body are concentrically arranged; and a thrust plate is arranged between the pump body and the rear pump body cover, and the rear pump body cover is provided with an inlet and an outlet which are matched with the thrust plate. The single-action constant flow paddle pump can be applied to all workplaces having requirements for the flow rate, and constant pump flow can be achieved.