A modularized knee joint cushioning structure includes a top joint seat connectable to a thigh, a friction adjustment assembly including an adjustment screw and coupled, in combination with a spring assembly, to the top joint seat and a bottom joint seat, a caliper forming an axle hole having a circumference forming a gap extending to the outside and including a bearing surface formed on an outside surface thereof, a main body having a main axle connecting the caliper and the top joint seat, and a bottom joint seat having a top end forming, at one side thereof, a brake block and coupled to the main body and the spring assembly. The spring assembly may alternatively used with a fixing assembly to limit the spring force of the spring assembly. The spring assembly is replaceable by a hydraulic assembly or a pneumatic assembly to form alternative cushioning structures.
