Composite membrane bags are produced on the basis of the composite filtering membrane. They use the high-density fabrics as support layers and are a new type of filter cloths with high-molecular polymer pressed and painted on them. The aperture is 0.2-12um, and the porosity is high above 80%. The main features are: smooth surface, resisting to acid and alkali, high filtration precision, high filtration speed, cake discharge rate, and especially fitting for the micro filtration of  about 1um aperture.