This article do some mechanism analysis on the way how the series cavity controls the aerodynamic noise by using the simple cavity model which comes to a conclusion that the front cavity can control the aerodynamic noise of back for the comprehensive effects of airflow derived and energy dissipation. Based on the mechanism, a control method of side-window wind buffeting noise was proposed, namely opening a groove on the B pillar to form a series cavity between the groove and interior space. Using large eddy simulation calculation method to firm the efficiency of the control method in restraining the generation of wind vibration, and then optimized the size, the result revealed when L/D=4, the noise can be reduced in maximum to 14dB.