Femtosecond detection technology can be used to observe the structure and morphology of the base film. Generally, the porous film is formed by the composite textile technology. The vent hole of the PE perforated film is funnel-shaped, and the air permeability of the funnel-shaped large opening toward the outer surface is 50-65. %, the surface of the small mouth is not easy to see through. The composite base film is a composite film composed of a nonwoven fabric and a PE perforated film.