A Bifidobacterium lactis BL-99 strain capable of enhancing immunity and the use thereof, which belongs to the technical field of microorganisms, is described. The Bifidobacterium lactis BL-99 provided by the present invention is deposited in China General Microbiological Culture Collection Center CGMCC on Apr. 26, 2018 with the deposit number CGMCC No. 15650. The bacteria have gastric acid resistance and intestinal fluid resistance, can significantly promote the growth of Bifidobacterium and Lactobacillus, significantly increase antibody-producing cells and half hemolysis value HC50, activate NK cell activity, and can be used to prepare foods for immunity enhancement. It also has the effects in preventing osteoporosis, increasing blood calcium and/or phosphorus ions, which has a wide range of application prospects.