The bag filter is a dry dust filter device. It is suitable for capturing fine, dry, non-fibrous dust. The filter bag is made of textile filter cloth or non-woven felt, and uses the filter function of the fiber fabric to filter the dusty gas. When the dusty gas enters the bag filter, the dust with large particles and large specific gravity is When the air containing fine dust passes through the filter material, the dust will be blocked and the air will be purified.