A plunger, a hydraulic end and a plunger pump are disclosed. The plunger includes a plunger body, the plunger body includes a flow channel; a first liquid inlet hole is located in the plunger body and passes through the sidewall of the plunger body; the plunger body includes a first end portion and a second end portion, a flow channel extends from the first end portion to the second end portion, a part of the flow channel close to the first end portion is closed, the flow channel extends to the second end portion and forms a first opening, the first liquid inlet hole is communicated with the flow channel, the first valve assembly is located at the first opening, and is configured to allow fluid to flow out from the flow channel at the first opening and prevent fluid from flowing back to the flow channel from outside.