Problems such as differential settlement of tunnel, structural deformation, seepage and instability of foundation pits and deformation of surrounding buildings exist in the construction and later operation of urban rail transit. The distributed optical fiber sensing technology is used to realize the deformation and differential settlement monitoring of long-distance tunnel segments of Ningbo Rail Transit Operation No. 1 Tunnel; and the Bragg fiber grating technology is used to realize automatic monitoring of tunnel cross-section and structural deformation. The monitoring results show that the segment deformation is small, which proves the effectiveness of optical fiber sensing technology in the monitoring of rail transit engineering structure, which is worth popularizing.