Abstract: To optimize the spray drying parameters,the cell survival rate(CSR)was taken as the evaluation index. The single factor experiments(SFE)was carried out to investigate the effects of protectant amount,inlet temperature,feeding speed,air intake rate and outlet temperature on CSR of Bacillus subtilis(B.subtilis)during spray drying. SFE results indicated that the feeding speed,air intake rate and outlet temperature were the most important factors. And meanwhile,a central composite design response surface methodology(CCD-RSM)was applied to explore the effects of feeding speed(X₁),air intakerate(X₂)and outlet temperature(X₃)on CSR,and a multivariate non-linear regression equation was established. ANOVA and regression analysis showed that the feeding speed(X₁)and air intake(X₂)had no significant effect(P>0.05),while the outlet temperature(X₃)had a significant effect on CSR(P<0.01).The optimal parameters of spray drying were confirmed by optimizing the model as feeding speed of 600 mL/h,inlet air rate of 80 m³/h and outlet temperature of 52℃. Under the optimized conditions,the confirmative test result was 96.64%±1.43%,which was well agreement with the predicted value. All results indicated that thermal-induced shock treatment and utilization of anti-thermal protectant could provide better protection of B.subtilis from thermal damages and maintain a higher survival rate. And the experimental results could also provide theoretical support for spray drying of Bacillus subtilis.