The invention belongs to the technical field of medical instruments and provides a medical treatment instrument. The medical treatment instrument comprises a treatment part, an operation part and a connecting rod part. The treatment part is provided with a pair of treatment instrument pieces. The operation part advances and retreats in the axis direction of the operation part relative to a base body, and therefore the treatment instrument pieces rotate to be opened and closed. The first end of the connecting rod part is connected with the treatment instrument pieces capable of rotating, and the second end of the connecting rod part is connected with the operation part. The distance between an advancing and retreating shaft of the second end and the first end is smaller than the length of the connecting rod part. The length of line segments, projected on the advancing and retreating shaft, for connecting the second end with rotary centers of the treatment instrument pieces is smaller than that of line segments, projected on the advancing and retreating shaft, for connecting the first end with the rotary centers. The medical treatment instrument is simple in structure and convenient to produce, machine, adjust and install, operation input can be provided to be efficiently transmitted, and large holding force can be generated with the low operation input.