A composite felt with sandwiched structure was prepared by evenly depositing basis of 150~400 nm electrospun soluble polyimide (P84) nanofibers on substrates of aramid nonwoven fabrics of 260~350 g/m2. The substrates were pre-sprayed electrostatically with high-temperature adhesives to bind the nanofibers. Another protective layer made of high-temperature nonwovens with basis of 40~60 g/m2 was used to shield the nanofibers. The composite was then hot-pressed to gain the binding strength as the adhesives solidified, to remove the simulated dusts, 0.3~10 ?m NaCl aerosols. The results showed that the property of the substrate was less affected by the adhesive, and the composite had a strength higher than 1000 kPa. Even a small amount of P84 nanofibers can obviously enhanced the filtration efficiency. The filtration efficiency of the composite reached to 100% to the particles equal and greater than 2.0 ?m, 99.5% to the particles 1.0~2.0 ?m in diameter.