Heating, Ventilation and Air Conditioning (HVAC) system of the high-speed train gets the most direct impact for passenger comfort, and the analysis of the passenger compartment temperature, humidity and micro air velocity is of practical significance. Numerical simulation of the three-dimensional turbulent flow in the whole flow field of the passenger compartment has been performed. Mass flow boundary conditions have been specified to the inlet and the outlet. The SIMPLE algorithm, in conjunction with the RNG k-ε turbulent model, has been used to solve the Navier-Stokes equations. Based on the numerical calculation of the internal flow in the passenger compartment, the velocity field, pressure field, temperature field and the micro air velocity have been farther analyzed. The calculation results have a good agreement with the experimental results, which are with good reliability. The research results are of important significance to the optimal design of the HVAC system for the train.