Abstract: Biotransformation processes have extensive applications in such fields as chemical industry，medicine，energy and environmental protection. The combination of membrane separation technology and biotransformation process not only expands the scope of research，but also provides strong technical support for saving energy and reducing consumption in industrial processes. In this paper，the applications of membrane technology in the processes of biotransformation such as fermentation，enzymatic catalysis，waste water treatment and fuel ethanol production are reviewed. The research progress and the existing problems in technology are also discussed，and the development prospect in the future is pointed out.