Knee joint protecting device

The invention discloses a knee joint protecting device and relates to the technical field of sports protective gears. The knee joint protecting device comprises a knee pad and an air cushion shoe andis characterized in that fixing straps are arranged on the upper portion and the lower portion of the knee pad, single-acting air cylinders are arranged on two sides of the middle of the knee pad, piston rods are fixed to the outer side of the knee pad through piston rod fixing straps, air cylinder bodies are fixed to the outer side of the knee pad through air cylinder body fixing straps, each air cylinder body is provided with an air cylinder air inlet and an air cylinder air outlet, and an air cylinder air outlet pipe is connected to each air cylinder air outlet and provided with an adjustable fast discharge valve; the bottom of the air cushion shoe is provided with an air storage cavity, the air storage cavity is provided with an air storage cavity air inlet and an air storage cavity air outlet, the air storage