Stevia sugar,the main chemical constituents of Stevia rebaudiana( Bertoni) Hemsl,is widely used as a sweetener because of its high sugariness,pharmacological activities,safety and low heat energy. Stevia sugar is a mixture of bitter and astringent remaining taste. This hindered its quality and its usage. Therefore,improving the processing techniques has become a hot research topic. In this paper,research progress of biological activity and product development of stevia sugar were reviewed. The paper provides some information on future research and application.