Abstract: The polyethylene terephthalate (PET) nanofiber membranes with different spinning times were prepared by electrospinning technique. The PET nanofiber membrane, hot melt membrane and polyester needle felt were heat-treated and composited to prepare the sandwich structure of PET nanofiber membrane/polyester needle felt composite filters. The morphology of PET nanofiber membranes and heat treatment conditions of nanofiber membranes were analyzed by SEM and TGA. The air permeability and filtration performance of the PET nanofiber membrane/polyester needle felt composite filters with different spinning times were studied. The results indicate that the average diameter of the fibers of PET nanofiber membrane is 514.95 nm under the conditions of 18% spinning solution concentration, 15 kV spinning voltage, 21 cm receiving distance, 13℃ ambient temperature and 20% ambient humidity. 115℃ is the suitable composite temperature of PET nanofiber membrane/polyester needle felt composite filters. With the increase of spinning time, the density and filtration efficiency of PET nanofiber membrane/polyester needle felt composite filters to particles increase, and air permeability decrease. With 3.86 g/m² density, the filtration performance of PET nanofiber membrane/polyester needle felt composite filters is the best, and the quality factor Q_F is obviously better than conventional polyester needle felt. The filtration efficiency of particles below 1 μm is higher than 93% and the efficiency is improved by 58%. The PET nanofiber membrane/polyester needle felt composite filters show excellent filtration performance.