Composite filter element

The utility model relates to the technical field of water purification, in particular to a composite filter element which comprises a filter element cylinder and a filter element seat, a first fastening structure is arranged on the outer side of the upper end of the filter element cylinder, the filter element seat comprises a top cover, a rotary fastener, a waterway plate and a pressing rod, the lower end of the top cover is open, the waterway plate is fixed inside the top cover, and the rotary fastener is rotatably arranged between the top cover and the waterway plate. A second buckling structure is arranged on the inner side wall of the rotating fastener and rotationally buckled with the first buckling structure, a connecting block is fixedly arranged at the center of the rotating fastener, a groove with an upward opening is formed in the connecting block, a plurality of inclined plane structures are arranged in the groove in the circumferential direction, and a plurality of sliding blocks are fixedly arran