Parameter inversion is an important means to obtain the material porous parameters, and the related principles and methods have been extensively investigated in recent years. The existing inversion researches are mainly based on the normal incidence acoustic model, while there is almost no investigation using irregular incidence sound model to invert porous parameters. This article studies the inversion method of porous materials under irregular sound incidence case. Here, the theoretical relationship was established between the porous parameter and irregular incidence absorption coefficient. The inversion study was conducted by using the established theoretical model, porous acoustic model and genetic algorithm, and the accuracy and astringency of inversed parameters was further analyzed. It's theoretically and numerically demonstrated that, the prediction and simulation results are in good agreement, and the inverted porous parameters by using irregular sound incidence model present high accuracy and astringency, which is expected to provide theoretical reference for porous parameter inversion analysis.