Rheumatoid arthritis（RA） is a common autoimmune disorder characterized by synovial inflammation of joints.Clinical treatment is based on the degree of disease activity.At present

disease activity score 28 is most commonly used to assess the disease activity

and its application is limited due to its complex calculation process and the need to combine with laboratory examination results.In recent years

the new technique of high frequency ultrasound（HFUS） occupies vital position in the diagnosis and treatment process of R A.This article reviews the progress of HFUS in evaluation of RA disease activity.