Porous fiber materials are the most widely used acoustic absorption materials at present, and they have excellent acoustic absorption performance. This paper uses the finite element method to explore the factors affecting the acoustic absorption performance of porous fiber materials, including flow resistance, thickness of the porous fiber material, incidence angle, and back cavity thickness. Due to the complex acoustic absorption mechanism of porous fiber materials, an equivalent fluid model is used to simulate the acoustic absorption properties of the porous fiber materials. The correlation of acoustic absorption performance and the model of the back cavity was analyzed. An impedance tube test was implemented to verify the simulation results.