Water pump and vehicle employing same

The invention provides a water pump and a vehicle employing the same. The water pump comprises a housing, a water pump shaft, an impeller and a hydraulic driving mechanism, wherein an accommodating groove is formed in the housing; the water pump shaft is at least partially arranged in the housing and can rotate around the central axis of the water pump shaft; the impeller is arranged outside the housing and is opposite to the accommodating groove, and the impeller and water pump shaft are fixed together; and the hydraulic driving mechanism is connected with the impeller and hydraulically drives the water pump shaft to move in the axial direction to change the degree of the impeller extending into or out of the accommodating groove. As the degree of the impeller extending into or out of the accommodating groove can be changed through the hydraulic driving mechanism, the water pumping capacity of the water pump can be adjusted and can be matched with the working condition with an engine, further, the fuel effic