The invention provides a pump, which comprises a shell, a motor fixed on the shell and an impeller driven by the motor, wherein the shell is provided with a cavity in which the impeller is accommodated, and an inlet pipe, a first outlet pipe and a second outlet pipe, which are communicated with the cavity; the first and second outlet pipes are respectively provided with a first opening and a second opening, which are positioned in the cavity and are opposite to each other; fluid entering the pump can flow in a direction from the first opening to the second opening or in an opposite direction under the driving of the impeller. The pump also comprises an elastic valve which is arranged between the first and second openings, wherein the valve can be deformed towards the first opening to seal the first opening or deformed towards the second opening to seal the second opening under the action of pressure of the fluid in different directions. According to the pump, a controller for controlling the valve is not required, so that the pump is lower in cost.