Considering the features of underwater shield tunnel with large cross-section, a prototype test of segmental lining structure for Nanjing Changjiang Tunnel (Φ14.5m) is carried out by using a new loading test method. And with “Multi-function Shield Tunnel Structure Test System” developed according to this test method, the effect of high hydraulic pressure can be equivalently imposed upon the structure by hoop, and then the earth pressure can be equivalently applied to the structure by radial concentrated force. The structures were loaded by the device according to a certain hydraulic and earth pressure. Meanwhile, the mechanical characteristics can be further studied. In a word, it can provide reliable test means for research, design and construction of underwater shield tunnel project.