The engineering Phase 1 of the rail transit Line 1 and Line 2 project in Hohhot is the very first rail transit project in China operated under the full-investment PPP mode in China, which considers the BIM technology as one of major means to implement informatized management. From the life-cycle application of BIM, this paper introduces the life-cycle BIM application system in details, including: the BIM application standard, the BIM data integration and management platform, the BIM application in all different stages of the project, and the digital asset delivery. Hence, a full set of life-cycle BIM application method is formed, providing guidance for the digital construction of urban rail transit.