Abstract: The construction of a new shield tunnel passing under the existing metro line often causes a superimposi? tion of surface settlement at the intersection area, which threatens the operating safety of the existing line. Based on shield tunnel construction from the Meicun station to the Shangmeilin station of Shenzhen Metro Line 9, this paper addresses the problems of earth-pressure build-up, settlement control and construction safety risks involved with the construction of an underpass adjacent to the shield launching end by using comprehensive technical construction measures and management means. These include: pressure maintenance using a steel sleeve at launching section, shield gap filling by the clay shock method,auxiliary grouting rectification, risk-zoning management, automatic real-time monitoring and theoretical analysis. These measures help to ensure the smooth construction of a shield tunnel under an existing metro line.