There are two cases of knee ringing when moving: 1, physiological ringing, that is, no disease ringing, this ringing when walking with a click click click click, but this ringing is not accompanied by pain, is due to thickened synovial membrane or thickened ligament friction issued by the ringing, not accompanied by pain, and no special treatment, no major problems; 2, pathological ringing, that is, the ringing of disease, is when walking suddenly click click joint lock can not move, accompanied by pain. The most common cause is meniscal damage or tear, in addition to joint free body, that is, joint rat, the joint in the proliferation of bone or degenerative cartilage fell out of the card in the joint, need to do surgery to deal with. Patients should go to the hospital for specific examination, X-ray, CT, and MRI to make a clear diagnosis.