Abstract: For studying the influence of the twin shield tunnel under-crossing on the buried culverts and offering the suitable reinforcement method, based on the real project construction parameters, the FLAC3D was adopted to numerically simulate the effects of unreinforced, only stratum surrounding culverts reinforced, only stratum around tunnels reinforced, and both strata around culverts and tunnels reinforced on buried culvert, and the results of numerical simulation were compared and analyzed. It was induced by above-mentioned methods respectively  that the largest vertical deformation of buried culvert is 26.3 mm,14.5 mm,12.7 mm and 6.8 mm, there was obvious stress concentration exiting on the culvert sections for the unreinforced method, there were the plastic zones appearing on the culvert deformation joints for the  former two methods, and there were not plastic zones appearing on the culvert deformation joints for the latter two reinforced methods. The last improvement method was very effective for reducing the deformation of culvert structures and surface subsidence.