Lactobacillus plantarum， as a probiotic， has many functional properties in the food industry， such as improved nutritional quality， flavor properties， antioxidant activity and antibacterial activity， which can be beneficial to health when consumed in sufficient quantities. However， probiotics are subject to various types of adverse environmental conditions in the gastrointestinal tract， particularly gastric acid and bile salts， which strongly inhibit their effective colonization of the active site in the colon with significantly reduced survival rates. To improve the stability of Lactobacillus plantarum in the human gastrointestinal tract and during processing and storage， microcapsules of Lactobacillus plantarum were firstly prepared by extrusion using whey isolate protein fibril and sodium alginate as wall materials. The effects of the mass concentration of the composite wall material and CaCl2 on the encapsulation effect of Lactobacillus plantarum were optimized by using the encapsulation rate as the index. The results showed that the optimum preparation conditions of Lactobacillus plantarum microcapsules were 2% mass fraction of WPIF， 2% mass fraction of ALG and 1% mass fraction of CaCl2， under which condition the highest encapsulation rate of Lactobacillus plantarum microcapsules was achieved at 92.13%. The stability of WPIF-ALG-L. plantarum 90 core-shell microcapsules were evaluated through in vitro gastrointestinal digestion for 5 h and storage at 4 ℃. It showed that the survival rate of WPIF-ALG-L. plantarum 90 core-shell microcapsules was 87.65% in simulated gastric fluid and 89.18% in intestinal fluid， and the survival rate was 79.98% after 25 d storage at 4 ℃. All results indicate that the core-shell microcapsules have good tolerance， intestinal solubility and storage stability.