NOVELTY - A combined undercurrent artificial wetland system comprises a rectangular wetland pond and a wetland bed body filled in the pond body. The wetland pond is formed by encircling the ground by a long-side dam and a short-side dam. A surface layer of wetland bed body is a small-particle size filling layer. The layer from surface layer to the bottom of pond is a large-particle size filling layer. The front end of the wetland bed body is a water inlet tube, and a sewage/waste water inlet tube is arranged. A water containing tank is arranged on the water outlet end.    USE - Combined undercurrent artificial wetland system.    ADVANTAGE - The system improves the total nitrogen removing rate, delays the wetland blocking, reduces the occupied area, and realizes the higher processing efficiency when operated at low-temperature or in winter.    DETAILED DESCRIPTION - A combined undercurrent artificial wetland system comprises a rectangular wetland pond and a wetland bed body filled in the pond body. The wetland pond is formed by encircling the ground by a long-side dam and a short-side dam. A surface layer of wetland bed body is a small-particle size filling layer. The layer from surface layer to the bottom of pond is a large-particle size filling layer. The front end of the wetland bed body is a water inlet tube, and a sewage/waste water inlet tube is arranged. A water containing tank is arranged on the water outlet end. The water containing side of water containing tank is water containing flower wall connected with fine grids and a water outlet tube is arranged in the tank. The fine grids are connected with large-particle size filling layer and small-particle size filling layer via a sand filter layer. The wetland plants with root portions penetrated into the large-particle size filling layer are uniformly distributed on the surface of wetland surface layer. An aerobic-anaerobic mixed region is arranged in wetland bed body, and an emptying tube is arranged on the lower part of wetland bed body. The water inlet end and water outlet end are arranged on the same end of wetland bed body, and the water inlet tube is a perforating tube horizontally placed between two long-side dams along the short side dam direction close to the front short side dam and embedded between large-particle size filling layer and small-particle size filling layer. The water containing tank is parallel to the water inlet tube, and arranged on the side of the water inlet tube away from the short-side dam at interval. Two ends of water containing tank are respectively connected with two long-side dams in sealing. A water-proof layer is arranged on inclined lower part of wetland bed body along the long-side dam. The upper part of water-proof layer is connected to the bottom portion of water containing flower wall, and a distance is remained between the lower and rear end short-side dams and the bottom of the pond. Two sides are respectively connected with two long-side dams in sealing. The upper part of water-proof layer is aerobic-anaerobic mixed region, and the lower part of the water-proof layer and the lower part of the water containing tank are anaerobic region. Vertical air discharge tubes with upper ends extended out of surface layer of the wetland bad body and the lower end penetrated to the lower part of the water-proof layer are uniformly arranged on the wetland bed body, and the tube body is connected with the water-proof layer in sealing.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic view of the combined undercurrent artificial wetland system.