The invention discloses a novel composite joint injury supporting instrument. The novel composite joint injury supporting instrument comprises a knee joint assembly and a foot joint assembly, whereinthe knee joint assembly comprises a thigh ring and a shank ring, connecting plates are mounted on the outer walls of the thigh ring and the shank ring, rotating shafts are connected between the connecting plates in a sleeved mode, wing plates are arranged on the outer walls of the connecting plates, and adjusting mechanisms are mounted between the wing plates and the rotating shafts; the foot joint assembly comprises a shoe cylinder, wherein a fixing plate is hinged to the bottom of the shoe cylinder, the bottom of the fixing plate is connected with a protective edge, the protective edge is connected with the middle of a sole, a U-shaped seat is mounted at one end of the sole and the outer wall of the shoe cylinder, and a damper is mounted at the middle of the U-shaped seat; and the thighring and the shank ring are connected to the thigh and the shank of the knee in a sleeving mode respectively, rotating resistance between the connecting plates is adjusted through the adjusting mechanisms, and therefore, the knee joint requirements of different patients are met. The shoe cylinder sleeves the lower portion of the shank, the feet of the patients penetrate into a protection head andthe protective edge, and rotation between the sole and the shoe cylinder is flexibly supported through the damper. The ankle joint requirements of different patients are met.