A femoral head prosthesis assembly and operation instruments thereof. The operation instruments include a hollow femoral neck holder with a configuration adapted to the surface configuration of the femoral neck and a shaper blade for cutting a replacement end of the femur into a predetermined configuration. A guide tube is disposed on a top face of the femoral neck holder. A transverse slot is formed on the femoral neck holder for indicating a femoral head cutting line. The femoral head prosthesis assembly includes a cap body and an artificial femoral head. A root section of the cap body has an inner surface in conformity to the surface of the femoral neck. A top section of the cap body has a cross section adapted to that of the replacement end. The cap body can be precisely securely bonded with the replacement end of the femur.