Abstract: Underground utility tunnel is inevitably affected by geological deformation when crossing active ground fissures. To investigate the influence of ground fissure activity on the mechanical behavior and deformation of precast prestressed utility tunnel structures, physical model tests were conducted to monitor the displacement of the utility tunnel, steel bar strain, and joint tensile displacement under ground fissure activity. The longitudinal deformation characteristics of the utility tunnel at different positions under various ground fissure settlement amounts were analyzed, and theoretical models for bending and tensile deformation were established. The test results indicate that under the action of ground fissure activity, the prestressed flexible joints lead to non-uniformity in the three-dimensional spatial response distribution of the prefabricated utility tunnel. Bending deformation, induced by the combined effects of shear forces at the hanging-wall joint and overburden pressure on the footwall, is mainly localized within the two segments spanning the ground fissure. Such bending deformation causes the outer side of the utility tunnel floor to be in compression and the inner side to be in tension, with the compressive stress being significantly greater than the tensile stress. For other positions, the axial strain of the utility tunnel is mainly affected by tensile and compressive deformation. The strain distribution law of the steel bars along the side lines of the utility tunnel roof and floor is basically consistent with that along the axis, but the overall strain value is reduced by approximately 20% compared with the axis. The deformation of the utility tunnel is affected by bending-tension-compression coupling, and the theoretical models show a high degree of fitting with the test results. The research findings can provide a theoretical foundation for the structural design of prefabricated utility tunnels in areas affected by ground fissure activity.