The bag filter is a multi-purpose filtration equipment with novel structure, small volume, simple and flexible operation, energy saving, high efficiency, airtight work and strong applicability. Bag filter is a new type of filter system. The inside of the bag filter is supported by a metal mesh basket. The liquid flows in from the inlet and flows out from the outlet after being filtered by the filter bag. The impurities are intercepted in the filter bag and can be used continuously after replacing the filter bag.