The product is composed of spunbonded protective layer, primary filter layer(PP melt-blown cotton), high-efficiency filter layer (nano fiber membrane) and spunbonded support layer by ultrasonic wave. The diameter of melt-blown non-woven fiber is 2-10 um, which can block large particulate matter with more than 2 um; the fiber diameter of nano-fiber membrane is 100-200 nm, and tthe formed three-dimensional porous structure can effectively separate 0.5 um, pollen, virus and other pollutants. The development of nano- fiber protective mask with virus protection function habeen completed. This protective mask adopts the gradient filtration effect of meltblown static cotton and nano-fiber composite structure from micron- scale to nanoscale. The filtration efficiency of 0.3pm standard particulate matter is more than 99.9% (test condition: on the full-automatic filter material test system TSI8130A, there are wind speed and flow rate with 15 L/ min and 0.3 um Naclartificial dust)ï¼?the filtration efficiency is still stable with more than 80% after the static electricity iscompletely removed. That can effectively protect and kill viruses is the preparation of nano-fibers with a diameter of 50-150 nm by the self-developed linear electrode electrospinning technology. The ultra-thin nonwoven filter materials with a filtration accuracy of 100 nm can be processed with such ultrafine fibers as raw materials, which can effectively intercept pathogen transmission media such as protective masky droplets, PM2.5, viruses, oily particulate matter, etc. Gradient filtration structure: the product adopts the composite structure of melt-blown static cotton and nano-fiber to realize the gradient filtration effect from micron-scale to nano-scale. Stable filtration performance: This product can be applied to all kinds of environments, such as humidity, disinfection and other environments, and can still maintain efficient filtration. This product mainly relies on pure physical filtration, after removing static electricity, the filber is stable with more than 80%, while the traditional electrostatic melt-blown cotton has only 15-25% filtration efficiency after removing static electricity. High filtration accuracy: This product uses ultra-fine nano-fibers as the core filtration layer, with the filtering accuracy less than 100nm, which can effectively intercept ultra-fine particles such as protective masky droplets, PM2.5, viruses, oily particulate matter,etc.