In order to explore the mechanical characteristics of shield tunnels passing through different soft-hard uneven strata, a three-dimensional refined shield tunnel numerical model considering the contact effect of ring longitudinal bolt joints and segment-soil was established, and its feasibility were verified by comparing the measured data. Then, aiming at the complex ground conditions of upper soft-lower hard, upper hard-lower soft, and longitudinal soft-hard uneven strata, the influence of different strata composite ratios on the internal force, convergence deformation and vertical settlement of shield segment structure was deeply explored. The results show that with the increase of strata composite ratio, the bending moment of tunnel bottom in upper soft-lower hard strata decreases greatly, the vertical settlement of segment increases slowly and then rapidly, and the convergence deformation of segment increases linearly. Compared with the upper soft-lower hard strata, the vertical settlement response of shield segment in the upper hard-lower soft strata is more sensitive under the same composite ratio. When the tunnel lies in the longitudinal soft-hard uneven strata, the extreme value and extreme difference of the longitudinal bending moment of the segment and the shear force increase with the increase of the strata composite ratio. The convergence deformation of the segment is larger on the hard soil side than on the soft soil side.