Abstract: Combining the uncertainty theory with the sound absorption structure model of the micro-perforated plate，the influence of the uncertainty parameters（thickness of the micro-perforated plate，sound velocity，air kinematic viscosity）on the sound absorption characteristics of the micro-perforated plate model was analyzed. A random-interval mixed uncertainty model was established for the study. In the model，the micro-perforated plate thickness was considered as a random variable and the sound velocity and air kinematic viscosity were used as the interval variables. And the correctness of the model was validated through the experimental and simulation analysis using Monte-Carlo method. The maximum frequency bandwidth corresponding to a certain value of sound absorption coefficient was selected as the optimization goal. The quality factor is greater than a certain value was setup as the constraint condition. Using genetic algorithm to optimize the structural parameters of the micro-perforated plate. The optimized microperforated plate structure has been improved in terms of sound absorption coefficient and quality factors. The analysis results showed that the sound absorption performance can be improved and verify the effectiveness of the random-interval mixed uncertainty model in the study of micro-perforated plate sound absorbers. It provides a novel method of the application of uncertainty theory in acoustic engineering.