Abstract: Fermentation has become a primary method for producing hyaluronic acid. Separation and purification are key steps of fermentation in preparing high relative molecular weight（Mr） and high purity hyaluronic acid. This article discusses the characteristics of fermentation broth and the influences of process conditions on hyaluronic acid Mr and structure，systematically analyzes the techniques in pretreatment，separation and purification stages. It also points out some existing problems in the separation and purification techniques and presents the focus of future research．