Abstract: Using gum acacia, β-cyclodextrin, soluble starch powder, gelatin and dry skim milk as wall-material, the best technical conditions for vacuum spray drying of micro-encapsulation of Lactobacillus acidophilus were determined according to orthogonal experiment, and the diameter and distribution of microcapsules were analyzed. The results show that the best wall-material is the mixture of β-cyclodextrin and gum acacia(9∶1), and the optimum concentrations of wall-material and core-material are 20% and 6%, respectively, inlet air temperature is 170℃. Under the optimized conditions, the survival bacterium number is over 10⁸ cfu/g, and the average diameter of microcapsules is 20 μm.