With the advent of quieter engine,the proportion of airframe noise has increased. Especially during the airplanes' approach for landing,high lift devices can be a prominent source of airframe noise. The paper focuses on discussing the noise principle,the noise reduction technologies and the prediction methods. Then introduces the flow characteristics of leading edge slat and trailing edge flap and elaborates the noise characteristics. After that,the application and development of several noise reduction technologies are summarized. At last the prediction methods are introduced.