Baby leg pain is divided into physiological and pathological changes. 1, physiological changes: the baby nocturnal paroxysmal pain without triggering factors, to exclude a series of pathological changes, considering growing pains, this is the baby in the process of growth and development of the muscles or joints pain, do not need special treatment, hot compresses can be slowed down. 2, pathological changes: synovitis, myositis, calcium deficiency, bone lesions, trauma and other triggering factors. Synovitis induced by viral bacterial infection baby limp, but the pain is slightly worse, for self-healing disease, about two weeks will be able to self-relief, but during the period must pay attention to rest, local hot compresses; polymyositis is an autoimmune disease mainly manifested by muscle weakness, muscle pain, at present the triggering factors are not clear, the main manifestation of muscular pain, especially in the legs. Early diagnosis is needed, appropriate rest, and medication is given to hormonal drugs for treatment; spasmodic pain caused by calcium deficiency, timely supplementation of calcium, the symptoms should be able to be relieved in about half a month; bone metastases of leg bone tumors, leukemia, or lymphoma can also have persistent leg pain, and local fractures caused by traumas are also accompanied by severe leg pain. Leg pain caused by different triggering factors and the way to improve it are different, so we must find out the cause and treat the symptoms.