A folded filter element structure, a filter cartridge device and a processing method thereof, the folded filter element structure includes a filter element frame, the filter element frame is connected with a ring-shaped folded filter element, the lower end of the filter element frame is provided with a lower cover; the filter cartridge device includes a filter cartridge and a The pleated filter element structure; during processing, one or more materials in the nuclear pore fine filter membrane, non-woven fabric, and nuclear pore coarse filter membrane are compositely welded together, and folded or not folded in half along the width direction and placed in parallel, and then along the The stretching direction is folded into a louver shape, and its two ends are sealed and welded to form a ring-shaped folded filter element; the folded filter element is placed on the filter element frame, and then the upper and lower edges of the folded filter element are welded to the upper and lower covers to form a sealed body; put the sealed body Insert it into the frame of the filter cartridge so that the upper and lower covers fit closely with the inner wall of the frame of the filter cartridge. The filter element of the present invention is self-contained, easy to replace, low in production cost, long in service life, has increased effective filtering area of the filter element, strong dirt holding capacity, improved filtering efficiency, reduced replacement frequency, more convenient use and wide application range.