The invention relates to a four-linkage brake knee joint. A knee base is disposed with a front through hole and a back through hole. An inner linkage connected to a cushion element is disposed inside the knee base. The joint further includes an OPPO body provided with an OPPO through hole in front and a pressing block in the back, two first linkages having an upper edge connected to the front through hole of the knee base and a lower edge connected to the OPPO through hole, two second linkages having an upped edge connected to the back through hole of the knee base, a clip disposed at the inner sides of the first linkages and the second linkages and having an upper through hole axially connected to the bottom of the second linkages and a lower through hole defined in the front bottom and corresponding to the OPPO through hole. The back of the clip is in contact with the pressing block. A gap is disposed at the upper through hole and has at least one bending section. The gap extends from the upper through hole down to the bottom of the clip. The opening is located between the lower through hole and the back of the clip.
