Abstract:Nattokinase（NK） is a microbial derived fibrinolytic enzyme with potential medicinal value. Compared with traditional thrombolytic drugs，NK has the advantages of safety，low cost，strong thrombolytic activity and oral administration. The solid and liquid fermentation are usually employed for the NK production. However，the current production capacity can hardly meet the requirements of industrial large-scale production. In this paper，the properties of nattokinase，the strain breeding，fermentation substrate selection，medium optimization，and culture condition optimization were summarized in order to provide reference for liquid fermentation and industrial production of NK.