The invention discloses a numerically-controlled turning damping vibration attenuation cutter bar. The cutter bar comprises a cutter bar body and a cutter head outside the cutter bar body. One end of the cutter bar body is provided with a cylindrical cavity. A vibration attenuation device is arranged in the cavity and comprises a spring, a damper, a vibration attenuation body and a connection piece. One end of the connection piece is cylindrical, and the other end of the connection piece is rectangular; and the cylindrical end is inserted into the cavity and is in interference fit with the cavity, and the rectangular end is provided with a round hole in transition fit with the cutter head. The two ends of the vibration attenuation body are each provided with a cylindrical boss. The cylindrical boss at one end of the vibration attenuation body is connected with the side face of the cylindrical end, and the cylindrical boss at the other end of the vibration attenuation body is clamped in the inner diameter position of one end of the spring; and the other end of the spring is connected with the round side wall of the tail end of the cavity, and the damper is composed of liquid polysiloxane filling in the cavity. The numerically-controlled turning damping vibration attenuation cutter bar is reasonable in structure and convenient to use and has a quite good vibration attenuation effect, so that the machining efficiency is improved, and the service life of a cutter is prolonged.