Abstract: In this study,a high-activity probiotic strain Bacillus subtilis OKF-004 which was screened by the laboratory was used for liquid fermentation culture. The single-factor experiments and orthogonal experiments were used to explore the optimal liquid fermentation medium components and culture conditions for spore formation. The obtained bacterial liquid was prepared by blast drying to prepare solid microbial agent,and the process for preparing the bacterial agent was optimized. It was most suitable for the formation of spores when the Bacillus subtilis was cultured in a medium containing 2.5% corn starch,3% soybean meal,and 2% glucose at initial pH of 6.5,liquid volume of 30 mL in 250 mL erlenmeyer flask,32℃,and inoculum size of 7%. The highest number of spores could reach 1.1×10¹⁰ CFU/mL. The bacterial sludge was reconstituted with a concentration of 5% of the protective agent glycerin at a ratio of 1:7 g/mL to prepare a bacterial suspension,and the shrimp head was used as a drying carrier,and the carrier and the bacterial suspension were mixed at a ratio of 2:3 g/mL.After drying at 50℃ for 6 h,the obtained bacterial agent had the best survival rate of 140.91%. The liquid fermentation culture and the solid microbial agent preparation method are simple in preparation,low in cost and suitable for industrial production.