Buffer type knee joint brace for treating knee hyperextension

The invention discloses a buffer type knee joint brace for treating knee hyperextension. The buffer type knee joint brace comprises a lower supporting piece, an upper supporting piece and a turntablepiece which are coaxially and rotationally connected; the turntable piece is provided with a plurality of gear grooves distributed around the circumference of a rotating shaft; the upper supporting piece is movably provided with a clamping piece elastically combined with the gear groove; a torque device connected with the turntable piece to drive the turntable piece to reset is arranged on the upper supporting piece; the lower supporting piece is provided with a limiting component used for preventing the turntable piece from swinging forwards and an unlocking component capable of driving the clamping piece to be separated from the gear groove; the upper supporting piece swings forwards relative to the lower supporting piece so that the clamping piece can be driven to be switched to be combined with the other gear