The invention discloses a boring cutter achieving feeding through inertia. The boring cutter comprises a boring cutter body. A rotating wheel is assembled on the boring cutter body in a rotating mode. The rotating wheel is provided with a ratchet wheel and a cam groove. A tool bit base which rotates along with the boring cutter body and is used for installation of a tool bit is movably assembled on the boring cutter body in a guiding mode in the radial direction. The tool bit base corresponds to the cam groove in position and is fixedly connected with a drive pin inserted into the cam groove. The cam groove is provided with a cam reducing curve pushing the distance between the drive pin and the rotation axis to be gradually enlarged. The inward and outward movement of the drive pin corresponds to the returning and feeding actions of the tool bit base fixedly connected with the drive pin. Radial feeding of the tool bit base can be achieved in the mode that the drive pin rotates along the cam groove by controlling engagement or disengagement of a pawl and a ratchet wheel, feeding of a ring groove to be machined is controlled, use is convenient, and the technical problem that an existing boring cutter cannot achieve feeding of the inner machining hole ring groove through actions of the existing boring cutter is solved.