Abstract: Based on the twin shield tunnel traversing beneath the subgrade of the high-speed railway, the numerical model of FLAC3D was established in the light of the soft clay conditions in Tianjing.Considering the factors of the CFG composite foundation, train load, backfill grouting, grouting pressure, Soil compartment of the working face pressure, staggering distance, underground water, all the process of the shield tunnel traversing the subgrade was simulated, and the lateral settlement of the top of the subgrade was analyzed.The study shows that the maximum value of the settlement on the top of the subgrade equals to 6.88mm, and the maximum settlement grade is 0.29‰.Settlement trough with unimodal shape was comparatively flat, and the settlement induced by the construction of the former tunnel isgreater than the later one.