The protection of underground utility lines is one of the difficult and critical points in the construction of Metro projects. A 1.8 m diameter castion watersupply pipe crosses the foundation pit of the running tunnel from South Railway station to South Sanhuan road station. The water supply pipe must be well protected in order to ensure normal water supply. Suspension protection is adopted for the water supply pipe. The scheme of the protection of the water supply pipe by means of universal bars is presented, structural calculation is made, and the construction technology is described with emphasis. The monitoring results show that the settlement of the water supply pipe meets relevant requirements and that the protection technology adopted is effective and reliable.