Abstract: The wind tunnel test section noise(pressure fluctuation) is one of the important indexes to evaluate the wind tunnel flow field, excessive noise not only significantly reducing the precision and accuracy of the collected data, but also arouses the model as well as wind tunnel parts buffeting response and causes serious fatigue damage to the materials, which is especially outstanding in transonic wind tunnels. This article discussed the causes of noise produced in the test section at first, with the common problems of general wind tunnels and the personalities of transonic wind tunnels included, and then based on wind tunnel tests studied sound laws of different test section wallboard type and model stand, analyzed the contribution for overall noise level from each component.