The filtration efficiency and resistance during the process of fluid flowing through filter materials is significantly influenced by the characteristic of filter materials, especially for air-filter materials which generally have a multi-fiber composite structure. Therefore, it is important to pay attention to the filtration efficiency and resistance of multi-fiber filter materials. In this study, theoretical equations of filtration efficiency and resistance were proposed based on uniform and multi-fiber composite filter materials, and series of experimental verifications had been implemented. The results indicated that the experimental results verified the theoretical equations well, which may accelerate the research and development of new air-filter materials.