Leg clicking can be caused by the following reasons: first, physiological ringing, there is cartilage attached to the knee joint, when flexing the knee joint or straightening the knee joint when the cartilage rubs against each other, there can be leg clicking sound, then it should be examined, if there is no disease, the diagnosis is physiological ringing, no need to carry out any treatment. Secondly, inflammation of the patellofemoral joint, when patellofemoral arthritis can have cartilage exfoliation or fragmentation, and lead to the sound of the leg ringing, this time to check the patellofemoral joint X-ray, MRI to diagnose. Third, meniscus injury, when the meniscus anterior and posterior horn has a tear, can also have the symptoms of knee joint popping, this time to check the MRI of the meniscus to diagnose. Fourth, disc meniscus, which is common in adolescents, is a congenital developmental deformity, and can have the symptom of clicking of the leg when walking, which should be diagnosed by MRI of meniscus.