Abstract: A secondary development of the groundwater flow simulation program MODFLOW was conducted with MATLAB software in this paper, which regards the continuously driven tunnel as a dynamic boundary condition, achieving a dynamic simulation of tunnel water inflows under ideal conditions. Three kinds of permeability coefficient fields were used as input for the model, and the calculation results show that: 1)the anisotropy of the permeability coefficient field has a great impact on simulation results; 2)a water inflow event will occur when a water-bearing zone in the tunnel is exposed, and the total water inflows will then gradually decrease until the next water inflow; and 3) the maximum water inflow occurs at the beginning of tunnel excavation in a defined location, then the water inflow at this location decreases in a negative exponential function with the attenuation law being related to the initial water flow and distribution of the permeability coefficient field of the simulated area. This study provides a theoretical reference for the prediction of water inflow during tunnel construction, while the model still needs to be improved according to actual formation lithology, structural conditions and construction progress in order to realize the real-time prediction of tunnel water inflow.