The invention provides a knee joint prosthesis. The knee joint prosthesis is internally provided with a thighbone part, a shinbone spacer, a shinbone platform and fixing columns, and the thighbone part is provided with a plurality of mounting positions; the upper surface of the shinbone spacer is matched with a first matching surface of the thighbone part, and the thighbone part is movably arranged relative to the shinbone spacer; the shinbone platform is used for being connected with a shinbone, the shinbone spacer is movably arranged on the shinbone platform, a second matching surface is arranged on the upper part of the shinbone platform, and the lower surface of the shinbone spacer is matched with the second matching surface; and the fixing columns are used for being connected with theshinbone, optionally connected with any one of the multiple mounting positions and located on the side, deviating from the shinbone spacer, of the thighbone part. Through the technical scheme, the positions of the fixing columns on the thighbone part can be adjusted according to the specific situations of the femoral condyle of a patient so as to effectively fix the fixing columns to the places,with the good bone quality, of the femoral condyle, thus it is ensured that the prosthesis is implanted reliably for a long term, and loosening and renovation are avoided.