Cold and painful knees may be caused by diseases of the knee joint itself, as well as lumbar diseases and vascular diseases of the lower limbs. 1. Knee joint disease: degeneration of the knee joint will cause pathological changes such as formation of bone cumbersome and synovial proliferation in the knee joint, resulting in blood circulation disorder and functional limitation of the knee joint, which will lead to cold and painful knees; patients with synovitis of the knee may also suffer from the above symptoms. 2. Lumbar diseases: Lumbar diseases may cause compression of the nerves innervating the knee area, resulting in abnormal sensory and motor functions in the knee area, which may also lead to symptoms of cold and painful knees, such as lumbar disc herniation and lumbar spondylolisthesis. 3. Lower extremity vascular disease: Lower extremity vascular disease can cause venous blood stagnation and pathological changes of limb ischemia and hypoxia, which may also lead to symptoms of cold and painful knees. Common diseases such as varicose veins of the lower extremities, arterial occlusive vasculitis and so on. Cold knee pain may also have other causes, 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.