Abstract: A widely applicable calculation method for the prediction of pressure transients during the train crossing in a railway tunnel is proposed based on one dimensional unsteady compressible homentropic flowtheory. Equations of boundary conditions are built formodeling the flowduring the crossing period, and a newgrid system for tracking the motion of trains is proposed. The proposed method is verified by comparing it with the practically measured pressure transients. The characteristics of the pressure transients during train crossing are also discussed.