Objective： Bifidobacterium lactis Probio-M8（B. lactis Probio-M8） is a beneficial strain with excellent probiotic properties. This test is based on the spray-freeze-drying process. The aim is to investigate the effect of process conditions on the quality of B. lactis Probio-M8 microcapsules and its characteristics after drying. Methods： To prepare Bifidobacterium microcapsules， the single factor and Box-Behnken response surface tests were used to optimize the optimal process conditions. The microcapsule morphology was observed using scanning electron microscopy. Gas chromatographic analysis was used to analyze the changes in the fatty acid composition of the bacterial cell membrane before and after drying. The tolerance of microcapsules was verified by simulating human gastrointestinal fluid， and its stability was explored. Results： When the drying temperature was 40 ℃， the peristaltic speed was 15 mL/min， and the nozzle diameter was 1.5 mm， the survival rate was 73.21%， and the microcapsule particle form was relatively complete. After drying， the unsaturated fatty acid content increased significantly by 10.53% （P<0.05）， maintaining the fluidity of the cell membrane. In the simulated human gastrointestinal fluid tolerance test， the average survival rate of B. lactis M8 in the capsule can reach 81.99%， which has good gastrointestinal fluid tolerance characteristics. Conclusion： By exploring the technology of spray-freeze-drying to prepare microcapsules， the preliminary determination of its optimal process conditions and its impact on the quality of microcapsules has opened up a new high-quality and rapid production of Bifidobacterium lactis Probio-M8 microcapsules on an industrial scale prospect.