Abstract: A rotating pneumatic knee joint structure is disclosed. The structure comprises a twisting connector module and a pneumatic module. The twisting connector module includes a rotating seat, an adjustable upper seat, adjustable screws, two rotating block modules, bearings, side-arch plate and axle, and screws and a plurality are used to lock all the components of the structure. A socket seat mounted at the thigh and a stop block within the rotating seat cause the lower limb connected to the pneumatic module to swing in a circular direction. Though the adjustable screw, and the spring support to hold the rotating block, the sole of the legs can be swing in a left or right direction so as to hold the weight of the user.