Abstract: The pressure wave owing to meeting in open air, meeting in tunnel and passing tunnel will generate effect on dynamic response and operation safety of high speed train. A high speed model including three vehicles is presented. Aerodynamic loads are obtained by CFD simulation. Dynamic response and derailment coefficient under the three aerodynamic condition are obtained by Runga-\!-Kutta method. Comparison and analysis show that the trains mutually repulsing when meeting in the open air and mutually repulsing attracting when meeting in tunnel. The aerodynamic load owing to meeting in open air and passing tunnel has little effect on derailment coefficient. Nevertheless, the aerodynamic load owing to meeting in tunnel will clearly affect derailment coefficient and safety performance.