Automatic cleaning bag filter

The utility model belongs to the field of water-treating equipment, particularly a bag type filter which can automatically wash. The utility model comprises a tank, an upper cover, a relevant pipeline and a valve, wherein a filtering bag is arranged in the tank. An inner net basket of a filtering bag is arranged in the filtering bag, an outer net basket of a filtering bag is arranged on the outside of the filtering bag, and a semi-circular barrier net is arranged on the outer net basket of a filtering bag is arranged in the filtering bag. The utility model can automatically remove short grained suspended substance and part of colloid, algae and dirt, with the advantages of high filtering precision, large water passage quantity and large dirt containing amount. The utility model adopts spiral type water in to lead large granules in water to fall quickly and centralize, which is convenient for exhausting. The speed of back flushing is high and back flushing is clean, which saves large quantity of purified water. In addition, the utility model also has the advantages of small size and light weight. The utility model can also be used for water desalting pre-processing and the processing to water of river water, lake water, water in a river and a pond, rain, sewage, intermediate water, underground water and tap water.