The patient is a 48-year-old male with bilateral knee gouty arthritis for more than 10 years. In the past 2 years, the joint pain has increased and the mobility has been impaired, and he cannot walk in bed. On examination, he saw bilateral knee swelling, pressure pain, a 70 degree deformity of the left knee in flexion, a 90 degree deformity of the right knee in flexion, a mobility of nearly 10 degrees, and both gout stones in the elbow and finger joints. x-rays showed a large number of hyperdense shadows around the knee joint and osteoporosis. Blood uric acid was significantly elevated. He was diagnosed with bilateral knee gouty arthritis and knee flexion ankylosis. After admission, he underwent gouty stone removal and artificial knee surface replacement. 14 days after surgery, he was discharged with basic knee extension and 100 degrees of flexion. The patient’s severe gouty joint deformity was rare.