The reason why babies cry when they walk may be due to leg injuries caused by trauma or joint pain caused by calcium deficiency. 1. trauma resulting in leg injuries: the baby is in a just learn to walk stage, walking is not very stable, sometimes fall, sometimes also touch down around some of the heavy objects pressed to the legs, this will cause leg muscle strain, serious fracture, will be accompanied by pain, then walking will aggravate the pain will be crying. 2. Calcium deficiency leads to joint pain: the baby is in a stage of rapid growth, bone growth is the need for a lot of calcium, if the calcium supplement is insufficient, will not be able to meet the growth needs, resulting in joint pain, walking pain obvious. Parents need to pay attention to the fact that babies cry when they walk, and should go to the hospital in time.