Abstract: In an effort to address the problems of aerodynamics in intercity rail transit tunnels and the difficulties of setting up relief sheds at tunnel entrances given the speedup of intercity rail transit trains, research on the changing transient pressure through the combination of an enlarged section and ventilation shafts was conducted for a highspeed metro tunnel. Additionally, a numerical simulation of three dimensional compressible, viscous and un-steady flow fields was conducted regarding changing pressure as a high-speed train passes through the enlarged section and ventilation shafts. Research results show that: 1) the enlarged section could decrease the air pressure wave and pressure gradient to some extent; 2) the wave-front pressure gradient and peak of the compression wave is effectively decreased with the placement of the enlarged section at a position 100 m to 150 m away from the tunnel entrance; 3) the length of the enlarged section has little effect on the air pressure variation in the tunnel, and it is ap?propriate for the enlarged section not to exceed the length of the train, i.e., approximately 200 m to 250 m long; 4) increasing the area of the enlarged section could also effectively decrease the pressure wave and pressure gradient in the tunnel; 5) a combination of an enlarged section and ventilation shafts could decrease the pressure wave and pres?sure gradient; 6) the ventilation shaft is positioned 10 m to 15 m within the enlarged section near the entrance of the tunnel.