In this paper, the contact stress of the spherical hinge is analyzed. By comparing the finite element model with the calculation results of the related contact theory, it is found that the distribution mode of the contact stress of the spherical hinge is similar to that of the vertical compressive stress distribution model of the spherical hinge, while Hertz contact theory is not suitable for analyzing the contact problem of the spherical hinge. In addition, the existence of unbalanced weight and inadequate contact between the upper and lower spherical hinges are studied in this paper. The results show that for a 30,000-ton swivel bridge, when the unbalanced moment is 0.5×104 KN·m~2.0×104 KN·m, the contact stress in the middle area of the spherical hinge increases, and the contact stress difference between the two sides also increases gradually, up to 16.97 % of the maximum contact stress. When the non-contact area of the middle of the spherical hinge is 10 %, 20 % and 40 %, the maximum contact stress and friction force at the edge of the spherical hinge increase by 9.41 % and 16.16 % respectively compared with the normal situation, but the total friction torque hardly changes.