The 3-dimensional unsteady compressible flows around the high speed train have been simulated for the train entering a tunnel and for passing another train. The simulation method employs the implicit approximation-factorization finite difference algorithm for the inviscid Euler equations in general curvilinear coordinates. A moving grid scheme is applied in order to resolve the train movement relative to the tunnel and the other train. The velo-city and pressure fields and pressure drag are calculated to study the effects of tunnel and the other train. The side directional force which is time dependent is also computed for the passing train. Pressure distribution shows that the compression wave is generated in front of the train noise just after the tunnel entrance and proceeds along the inside of tunnel.