Research conclusions：(1)The Tertiary sandstone has complex water-sensitivity．Under groundwater condition． plastic deformation or flowing deformation occurring in the rock mass caused high difficulty during construction．(2)By conceptualization of the computing cell boundary conditions，we set up the hydrogeological conceptual and mathematical models by using the MODFLOW，and simulated the seepage field of Tertiary water-bearing sandstone and calculated the maximum velocity and water inflow of the tunnel．(3)Compared with the conditional water inflow calculation methods in excavation，the numerical simulation method did more tally with the actual situation of water-inflow． (4)The methods of seepage field simulation and water-inflow calculation in this study has certain reference significa nce for hydrogeological condition analysis in homogeneous water-bearing strata．