Particulate matter (PM) pollution is a global problem. It is of great significance to develop an advanced PM_0.3 air filter. In this paper, the factors affecting the fiber diameter in spinning are discussed, and a kind of organic-inorganic hybrid ultrafine nano-fiber membrane with high-efficiency and low-pressure drop is prepared via utilizing low viscosity electrostatic spinning solutions. The viscosity of the spinning solution is diminished via reducing polyvinylidene fluoride (PVDF) mass fraction and adding hydrophobic silica (SiO₂). In this way, the mean fiber diameter of the hybrid nanofiber membrane = 53.08 nm, mean pore size = 0.43 μm, and the surface potential is as high as 17.53 kV. Hence, the filtration efficiency of PM_0.3 is as high as 99.997%, and air pressure is comparatively low (only 114.46 Pa). In conclusion, PVDF-SiO₂ fiber membrane can effectively accomplish high-efficient and low-pressure air filtration and can be widely used in various fields such as various masks and protective clothing.