Aimed at head car of EMUs, according to different types of seals used for different types of openings on the car body, test equipment was designed for testing air tightness of different holes, and air tightness of EMUs was evaluated by the experiment data and evaluation means. Through the results, the following conclusions about air tightness was understood: pressure alteration testing could evaluated the leakage area of whole car-body and different hole part, air tightness of EMUs accorded with interrelated standards.