Abstract: The structures of micro-perforated panel were applied in the measurement to characterize the sound source in a duct system base on attaching the side branch tubes.The effect and influence to change the acoustical impedance of the loads in a duct system when we used one layer and two layers micro-perforated panels and back cavities with different parameters(like panel thickness,hole diameter,perforation ratio,back depth and so on)were analyzed and simulated. The results show that the load's resistance can be changed efficiently by adjusting panel thickness,hole diameter, perforation ratio,the ratio of cross-section between ducts and tubes and other parameters.;the load's reactance can be changed efficiently by adjusting back depth and distance between micro-perforated panel and main duct;the combinative usage of one layer and double layers of this structures can change the reactance substantially in broad frequency domain. By the experiment under the situations of flow and no-flow,the correctness of the method and the efficient performance of the structures with micro-perforated panel in the measurement were verified.The suggestion to design and apply these structures in the above-mentioned method in application was given out.