Basing on FLAC3D (Fast Lagrangian Analysis of Continua), the shield tunnel construction process is simulated, and the influence factors and their interaction for modeling are analyzed. Firstly, combing the influence factors on the reciprocity of the shield precursor with the rock-soil mass, the excavation process is simulated; at the same times, the tunnel ground subsidence and the tunnel upper vertical stress are calculated. Secondly, by mean of removing one of the factors from the stimulating model respectively, the parameters corresponding with them are also calculated. Finally, basing on Fast Fourier Transform, the ground subsidence and the vertical stress are analyzed by comparison, and the influence effects for modeling of all kinds of the factors are found out. Experimental results show that, on one hand, the influence effects to the ground settlement are more than to the vertical pressure of the tunnel; on the other hand, the factors to the simulation results include the soil-rock stress of the excavation workface causing by the shield boost, the temporary low support strength causing by the grouting at the end of the shield delaying the shield tunnel segment assembled and the soil-rock torsion force of the excavation workface causing by the shield cutterhead running.