Abstract: Particulate matter (PM) pollution in the air has become a serious environmental problem, and therefore highly efficient air filters need to be developed to cope with these. In this work, we used solution blow spinning (SBS) and mist spraying to modify the surface of polyacrylonitrile (PAN) nanofiber membranes with high aspect ratio of boron nitride nanosheets (BNNSs) to build a hierarchical structure, thus enhancing the specific surface area of nanofiber membranes and effectively capturing PM pollutants. The results show that the 4-BNNSs/PAN air filtration membranes with graded structure have 95.13% filtration efficiency and 34 Pa pressure drop for PM2.5, which is 9.46% higher filtration efficiency and only 13 Pa higher pressure drop compared with PAN filtration membranes with the same spinning time, resulting in better overall filtration performance. This work reveals that the construction of hierarchically structured BNNSs/PAN composite membranes by mist spraying BNNSs onto the surface of PAN nanofiber membranes is a practical modification technique for the development of new air filtration membranes.