Bag filter is a dry dust filtering device. It is suitable for capturing fine, dry, non-fibrous dust. The filter bag is made of textile filter cloth or non-textile felt, using the filtering effect of fiber fabrics to filter the dusty gas. When the dusty gas enters into the cloth bag dust collector, the particles of large, large dust, due to the effect of gravity will settle down and fall into the dust hopper, and when the gas containing fine dust passes through the filter material, the dust will be blocked, so as to make the gas be purified.