Disclosed is the use of Bifidobacterium lactis BL-99 in the protection of cartilage. Provided in the present invention is the use of Bifidobacterium lactis in the preparation of a composition for protecting cartilage, wherein the Bifidobacterium lactis is Bifidobacterium lactis with the deposit number of CGMCC No. 15650. The Bifidobacterium lactis can promote the development of cartilage, increase cartilage density, protect cartilage from damage, promote cartilage repair and/or ameliorate cartilage damage, and is beneficial to cartilage health.