Introduction: This fabric is made of permanent fire resistant polyester yarn, adding a certain amount of negative oxygen ions mineral powder, the fabric perfroms good at fire resistance after repeated washing. It has the function of permanent release of negative ions, and this function will not be effected after washing. Experiments show that, under the dynamic environment, this fabric releases three times more negative ions than under static environment, so this fabric is a great material for duct, because it can continuously produce a large amounts of negative ions under constant air supply conditions. For a long run, it can improve indoor air quality, clean the dust particles, and remove indoor odor. This fabric also has a natural anti-mite effect.