Abstract: An experimental investigation has been carried out on a kind of perforated liner with a bias flow through the apertures,according to Howe’s vortex sound theory.The attention was focused on the effects of the aperture size,the cavity depth and the perforated plate thickness on the impedance of the liner.The algorithm of the reactance is modified for the liner with thick perforated plate,based on the analysis of experimental results.The perforated liners with sucking and blowing bias flow are compared and the same conclusions are drawn out.