Children with fever and knee pain may be caused by common cold, rheumatic fever, juvenile idiopathic arthritis or other causes. 1. Common cold: Common cold is usually a viral infection, which can cause systemic reactions such as muscle aches, knee pain and other symptoms in addition to fever. 2. Rheumatic fever: this disease is an acute or chronic systemic connective tissue inflammation caused by hemolytic streptococcal infection. Clinical manifestations are often dominated by arthritis and carditis, which can be seen as fever, skin rash, joint pain and other symptoms. 3. Juvenile idiopathic arthritis: it is a common rheumatic disease in childhood, mainly characterized by chronic synovitis, with typical symptoms such as fever, joint pain and skin rash. 4. Other causes: such as leukemia, knee tuberculosis or tumors, etc., can appear fever accompanied by knee pain symptoms. Children’s fever knee pain, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.