The invention discloses a hydraulic rotor speed change mechanism. The hydraulic rotor speed change mechanism comprises a rotating body, a hydraulic pump and an injection channel, wherein the hydraulic pump is arranged on the rotating body; a shell of the hydraulic pump is fixedly connected with the rotating body; the injection channel and the rotating body are arranged in a torque manner; a liquid outlet of the hydraulic pump is communicated with a medium inlet of the injection channel. The hydraulic rotor speed change mechanism disclosed by the invention is simple in structure and is suitable for rotating power with various rotating speeds; moreover, the speed of the rotating power with extremely high rotating speed can be changed conveniently.