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.