The nasal cavity filter is an invisible air purification device, which pushes the filter into the nasal cavity and filters out unclean particulate matter through a built-in filter to achieve the effect of filtering air. People with this filter can always inhale fresh and clean gas. The product is compact and easy to carry, commonly known as "invisible mask", which does not affect face-to-face communication with others when used, and at the same time solves the characteristics of wearing a mask for poor breathing and long-term use of moisture.