Double layer filter bag refers to the filter bag made by connecting two layers of material through welding or seam processing. Compared with the conventional single layer filter bag, the filtration effect of double layer filter bag will be better. In the process of making a double filter bag, the filtration accuracy of an inner layer is a little larger, the outer layer is a little smaller, that is, the inner thick and the outer dense, through this combination structure, to achieve more effective filtration effect