PTFE nano mask film is a film formed by biaxial stretching of polytetrafluoroethylene dispersion resin as raw material, and its fiber is a nanoporous film with a honeycomb network structure. It has the advantages of low breathing resistance, high filtration efficiency and continuous stability. At a flow rate of 95L/min, the resistance is less than 100Pa and the filtration efficiency is greater than 98.5%.