Leg pain in a 4-year-old child may be caused by excessive exercise, vitamin D deficiency or calcium deficiency. 1. Excessive exercise: Excessive exercise can lead to strain on the joint muscles, which usually results in symptoms such as leg pain, so excessive exercise may lead to leg pain in a 4-year-old child, and it is recommended that the child take proper rest and perform local massage, which can alleviate the child’s symptoms. 2. Lack of vitamin D or calcium deficiency: children lack of vitamin D or calcium deficiency, may lead to lower limb muscle spasms, localized pain and other symptoms, so the lack of vitamin D or calcium deficiency, may also lead to 4-year-old children leg pain. It is recommended to take appropriate calcium supplements, such as soy milk products, meat, eggs and other foods. Therefore, 4-year-old children with leg pain, it is recommended to seek timely medical attention to identify the cause and timely treatment, so as not to affect the normal life of the child in the future.