Klippel-Trenaunay Syndrome ( KTS ) is a rare congenital vascular disease. The disease is mainly characterized by vascular malformation, varicose veins, soft tissue and bone hypertrophy. The incidence of KTS is 2 / 100,000 – 5 / 100,000 in live births. Most of KTS are sporadic, with few familial genetic tendencies. The etiology and pathogenesis are not yet clear, and there is no clear treatment plan. Conservative treatment or surgical treatment can be adopted according to the condition. Severe knee arthritis caused by KTS is more rare. Total Knee Arthroplasty ( TKA ) is considered to be the gold standard for the treatment of end-stage knee arthritis. This paper reports a typical KTS patient with severe knee arthritis who underwent total knee arthroplasty to improve the clinical understanding of the disease.