Abstract: In order to study the deformation and force distribution of shield tunnels, distributed optical-fibre monitoring was carried out in a shield tunnel. During the prefabrication of the shield tunnel segments, the optical fibres were arranged on the upper and lower surfaces of the reinforcement cage inside the segments, along the circumferential direction. The distributed optical-fibre monitoring was conducted after the segments were installed and after the segment deformation was stable, and the strain distribution inside the segments was obtained. The displacement, force and load distribution of the segments during the monitoring were calculated based on the continuous strain data, using the proposed inversion analysis method. The inversion calculation results showed that the deformation mode of the shield tunnel during the monitoring was the coupling deformation of the leftward oblique ovalisation and the overall circumferential compression. It can be seen from the force distribution that the fluctuation of the forces at the segment joints was obvious, which was caused by the change of stiffness at the segment joints. To reflect this fluctuation, the beam-spring model is more suitable for the segment design. The failure envelope diagram of the segments was developed, and the force values obtained by the inversion analysis were marked in it. The dangerous cross sections were selected to check the structural safety. The calculation results proved that the tunnel segments were safe.