Abstract: To optimize the high density continuous fermentation process of Vitamin K2,the effects of raw materials concentration,rotation rate,p H,dissolved oxygen( DO) and post- processing techniques were investigated by the fermentation of Bacillus subtilis natto.It was found that the optimal condition was of Glycerol 5%,soybean protein2%,mushroom compost 3%,p H7 and DO of 20% at 600 r / min. The highest yield reached 35.58 mg / L in 5 L fermentation tank.Mushroom compost,as a supplementary nitrogen source,can promote the biosynthesis of VK2,and its effective concentration was 3%. The fermentation broth was extracted by extract liquor and filtered by nanofiltration membrane.As a result,Vitamin K2 can be well isolated and the VK2 mixed mushroom powder was obtained through spray drying. The structure of Vitamin K2 was characterized by HPLC and MS. The quality of product was safe and qualified.