Children with leg pain need to be alert to the presence of knee synovitis, tuberculous hip arthritis, osteochondritis dissecans, bone tumors and other diseases. 1. Knee synovitis: mainly due to knee sprains and a variety of intra-articular injuries, children can have different degrees of pain in the joints as well as restricted activities, etc. It is recommended to improve the examination in a timely manner, and to avoid substantial joint activities. 2. Tuberculous hip arthritis: this disease is easy to occur in preschool children. It is mainly unilateral and usually develops slowly. It can be characterized by pain in the affected limb, and in severe cases, the child may even be woken up at night with pain. 3. Osteochondritis dissecans: this disease is common in children’s thigh roots, is a kind of cartilage necrosis disease, mostly related to the children’s excessive activity, usually in the cold or after strenuous exercise leg pain, and there is a tendency to gradually aggravate, it is recommended to take the children to timely examination and treatment. 4. Bone tumor: for example, chondroma, osteosarcoma, osteofibroma, etc., which can produce bone destruction and periosteal reaction, and then cause lower limb pain, and different treatments can be taken according to the doctor’s instruction, such as radiotherapy, chemotherapy, surgery and so on. 5. Others: For example, when the infection of bacteria, virus and other pathogens is more serious and causes systemic symptoms, there will be muscle pain and weakness in limbs, including leg pain. It is recommended to clarify the cause of the infection and carry out anti-infection treatment. In conclusion, leg pain in children can be caused by many reasons, if the duration of leg pain in children is longer and the pain is severe, it is recommended to consult a doctor in time.