Total knee arthroplasty (TKA) has been successfully applied for the treatment of the knee pathology at the end stage such as osteoarthritis and rheumatoid arthritis. Although TKA has became a very mature technology, some patients still suffer from the persistent pain after surgery. The cause of this pain have been recognized as the operation or technical error in most cases, and it usually requires a surgical intervention. Only when the cause of pain is judged accurately, can the operation and other factors be estimated correctly, determining the appropriate treatment methods. In the article, the causes of the post-operative pain after TKA are reviewed, which may be helpful to study the causes of the pain, and to decrease the occurrence incidence of pain.