Calf pain in a four-year-old child may be considered to be related to physiological factors, or it may be caused by trauma and other reasons. 1. Physiological factors: growing pains are the most common. Growing pains are a physiological phenomenon unique to children’s growth and development, usually without localized redness, swelling, pressure and pain. However, they may cause pain around the knee joint or the front side of the calf at night. This condition does not require special treatment. 2. Trauma: when the calf suffers from trauma, it may lead to bone contusion, fracture, meniscus around the joint, ligament and soft tissue damage, which will lead to redness, swelling and pain in the calf. 3. Others: such as acute septic arthritis, acute osteomyelitis, osteoarticular tuberculosis, rheumatoid or rheumatoid arthritis, interosseous hemangioma, osteogenic sarcoma and other diseases can lead to calf pain symptoms. When a four-year-old child has symptoms of calf pain, parents are advised to bring their children to the hospital in time, after clarifying the specific causes of the disease, under the guidance of the doctor for targeted treatment.