Abstract: PAN nanofibrous porous membranes from different solution concentrations were prepared by electrospinning, and then the morphology, diameter of fiber, porosity and specific surface area, mechnical properties and filtration efficency of the fiber membranea were tested and analysised. The results show that the average diameters of nanofibers increase as the concentrations of spinning solutions rise, the as-spun nanofibrous porous membranes which exhibit good overall mechnical properties show lower filtration efficiency, the sample 2 presents the best filtration efficiency among them. When the filtration rate is 5.3 cm / s and experimental particle size is 0.06 ~ 0.43 μm, its filtration efficiency is between 99.9% and 99.993%, better than the commonly used high filter. Moreover, its most penetrating particulate size is about 0.10μm.