NOVELTY - A vertical subsurface-flow constructed wetland sewage-treatment comprises providing water distribution system in an upper part of wetland substrate; after distributing sewage on a level section of wetland, flowing sewage down for purification; and providing catchment system in a bottom of wetland substrate to collect and discharge sewage distributed on the level section of wetland. The sewage-treatment system comprises wetland plant, water distribution main pipeline, water distribution pipe branching, small grain size substrates, medium grain size substrates, and header.    USE - For vertical subsurface-flow constructed wetland sewage-treatment.    ADVANTAGE - The method does not plug wetland under high loading of feed-water, and purifies sewage effectively. The sewage-treatment system is convenient to build at low cost and achieves simple operation and managing.    DETAILED DESCRIPTION - A vertical subsurface-flow constructed wetland sewage-treatment comprises providing water distribution system in an upper part of wetland substrate; after distributing sewage on a level section of wetland, flowing sewage down for purification; and providing catchment system in a bottom of wetland substrate to collect and discharge sewage distributed on the level section of wetland. The sewage-treatment system comprises wetland plant, water distribution main pipeline, water distribution pipe branching, small grain size substrates, medium grain size substrates, and header. It operates by feed-water constantly. Pipe branching is distributed equally in the wetland part, where lower part of which is 5-10 mm-medium grain size substrates. The header is located at the bottom of medium grain size substrates. Small grain size substrates are located in strip along the water distribution pipe branching direction, the surface of which is planted with wetland plants. Sewage seep along plants roots to form infiltration flow. Medium grain size substrates fill the space among each strip small grain size substrates until surface. Reoxygenation corridor is barely formed on the medium grain size substrates surface. Sewage contacts with gases passing in and out from reoxygenation corridor in the spacing, processes with micro-organisms, substrates, and plant roots, and then discharges from catchment system. Gases enter each substrates and spread to water in the water distribution zone through gas reoxygenation corridor surface spacing, which makes substrates and microorganisms on the roots on nitration environment. Sewage purifying is finished in medium grain size substrates, in which there are plant roots and microorganisms. The wetland plants are xeric or hydrophytic plants comprising sward, Typha, reed, India Canna, balsamroot, rush, and giant reed. The small grain size substrates is the covering layer of medium grain size substrates, which are soil, sandy soil mixture, or gravel and soil mixture. The medium grain size substrates comprise furnace dregs, gravel, or coal clinker.