Abstract: The geometric parameters of micro-perforated panels with irregular holes cannot be directly known, making it difficult to calculate the sound absorption performance. Therefore, a method of estimating the geometric parameters of micro-perforated panels is proposed. The irregular holes are treated as equivalent circular ones, and the model of estimating the geometric parameters is established by using Maa's theory about the panel with circular holes. The result of the parameter estimation of a type of micro-perforated panel is used to predict the absorption performance,resulting in good agreement with experiments. According to the influence of the geometric parameters of the panel on the high absorption area, the relationship between the application limit of Maa's theory and the geometric parameters is discussed, and the evolution law of the sound absorption performance of the panel polluted by dust is investigated. When the parameters of the panel are designed near the center of the high absorption region, large value of the application limit of Maa's theory can be obtained;and if the parameters are located in the upper right part of the high absorption area, a certain degree of dust pollution of the panel does not reduce the sound absorption performance.