Abstract: Bacillus subtilis is a widely used probiotics,which can maintain the balance of intestinal micro-ecology and improve the immune level of the body, which plays a unique role in the biological control of plant diseases and the promotion of plant growth and development. It is widely used in the fields of biological preservation,animal breeding,crop disease and insect control,animal nutrition and biological fertilizer production because of its easy artificial production and high environmental friendliness. In this paper,the function of Bacillus subtilis was analyzed,the application of Bacillus subtilis in biological preservation,animal breeding,crop disease and insect control were mainly described,and the prospect of new development and application of Bacillus subtilis was put forward.