Abstract: In order to improve the viability of Lactobacillus acidophilus, a novel microbial ecological agent in style of microcapsule was made by extrusion method and freeze drying in this study.Orthogonal test was used to filter the best formula of preparation of microcapsules. The result showed that with skim milk powder concentration of 4% ( w/v) , sodium glutamate concentration of 1.5%, sodium alginate concentration of 3%, calcium chloride concentration of between 1.62% and 2% , the survival rate of Lactobacillus acidophilus reached 99.21% , the number of bacteria’s livability reached 8.9 × 10 11 cfu /g, and the product had good acid resistance and intestinal- lysis, and it had good storage stability.