In order to research the real mechanical behavior of the supporting system during urban bridge long stroke synchronous jack-up under specific boundary conditions, the comparative stress analysis of space calculation results and truss structure calculation is adopted. From the perspective of the simulation calculation method, this paper carries on analysis on the simulation calculation method of the lifting support system which is constituted by the steel support, pile caps, artificial dig-hole pile three a whole. The results show that the accuracy of the traditional support system calculation method which is based on elastic foundation beam hypothesis is not high and often cannot reflect the space mechanics state of supporting system. In this paper, the ABAUQS space simulation is adopted to lifting support system during which the nonlinear characteristics of the structure is considered, the convergence is good .The space calculation method of the lifting support system which is constituted by the steel support, pile caps, artificial dig-hole pile is more accurate than “m” method.