Lactic acid bacteria is an important probiotics in body. Because of its function and safety benefits, it has been widely used in the food industry and health care. In addition, Lactic acid bacteria, as an oral vaccine carrier and drug delivery carrier, has become a hotspot of research. However, the survival capability of Lactic acid bacteria is limited by the harsh environment of gastrointestinal tract. In this article, we used chemical method to prepare calcium alginate microcapsules of Lactococcus lactis, which can express Gfp stablely. Then we used Gfp as a viable marker to test the protective effect of calcium alginate microcapsules on Lactococcus lactis. In vitro experiments, it is showed that after acid treatment 30 min, 60 min, 90 min, 120 min, the survival rates of calcium alginate microencapsulated Lactococcus lactis were increased by 1 370, 525, 235 and 105 times, respectively. In vivo experiments, after 2 h stomach gavage, the number of alive Lactococcus lactis in calcium alginate microencapsules was increased by about 90 times in the intestine. The results suggested that microcapsulation of Lactococcus lactis with calcium alginate had significant protective effect on Lactococcus lactis in the gastrointestinal tract environment and provided an important frame for Lactococcus lactis in the future research of oral agents.