Abstract: In this paper，the structural design and installation mode of air supply duct for passenger rooms are briefly described and the concept of multi-directional air supply and return system for metro vehicles is put forward. A numerical simulation of flow field in air supply duct and indoor flow field is carried out by using computational fluid dynamics（CFD）. The results show that after adopting the multi-directional air supply and return system，the deviation between the predicted air volume and the theoretical air volume at each outlet of the air supply channel is within 15%，and the uniformity of the air outputs is good. The velocity field and temperature field in the moving area of the carriages are evenly distributed，the breeze speed is between 0.2m/s~0.42m/s，and the vertical temperature difference of the section is less than 3℃. The adoption of the multi-directional air supply and return system in metro vehicles not only improves the comfort of pas⁃sengers in the seat and door areas，but also reduces the wind speed in the middle of the carriage and alleviates the blowing sense of passengers.