Abstract: The pressure difference inside and outside car body and the local pressure changes of seals cause the sound transmission increase of the sealed door, when the car is running at high speed. However, there are few related researches on this problem at present. In the current research, by using the small-scale aero-acoustic wind tunnel test methods and referring to the interactive characteristics of the seals and the aerodynamic forces of an actual car door structure, the experimental conditions and the test pieces of the door sealed at a single side and the door sealed around are prepared for the study of the sound transmission characteristics of the seal structures. It is found that the vertical and horizontal seals have a greater impact on the sound transmission of the door at middle and high frequencies, the frequency range extends to low frequencies for the horizontal seal, but there is little effect at high frequency. Acoustic radiation and transmission characteristics in airflow are further analyzed. The sealing strip compression force has a positive correlation with the sound transmission of the sealing structure, but it is affected by the four sides supports, internal and external pressure difference, deformation of the door structure, and the force on the sealing strip. The research has an important reference value for the design of door sound insulation and sealing.