Abstract: To improve the stability of Bifidobacterium animalis subsp. lactis BB12, Bifidobacterium microcapsules were prepared using water-insoluble dietary fiber in banana peel-sodium alginate-carrageenan composites as wall materials. Based on the single-factor experiment and hill-climbing test, embedded yield was used as the response value, and Box-Behnken test was used to establish a regression model for variance analysis. The characteristics of the microcapsules were evaluated by structural characterization and simulated digestion conditions. The results indicated that the optimized conditions for preparation of Bifidobacterium microcapsules were as follows:Content of water-insoluble dietary fiber in banana peel was 46.00%, concentration of sodium alginate was 2.70%, concentration of carrageenan was 5.60%, concentration of Fructo oligosaccharides was 2.60%, and stirring time was 31.00 min. The embedded yield under the optimized conditions was 73.02%. Infrared spectroscopy analysis showed that Bifidobacterium was embedded in the composite wall material and microcapsules were formed. In addition, the inside of the microcapsule was loose and porous, as observed under scanning electron microscopy. The prepared bifidobacterial microcapsules had good tolerance in the conditions of simulating gastric juice and high bile salt solution. This study laid the foundation for further development and utilization of water-insoluble dietary fiber and probiotic microcapsules.