Multi-medium constructed wetland water treatment system

The utility model relates to the water treatment field, and particularly relates to a multi-medium constructed wetland water treatment system. A constructed wetland device is composed of a horizontal subsurface flow wetland device and a surface flow wetland device which are connected by a branching pipeline, wherein wetland plants are grown on the upper part of the wetland device; a plurality of filter layers are paved inside the horizontal subsurface flow wetland device; water is purified via each filter layer of the horizontal subsurface flow wetland device; the plurality of filter layers comprise a substrate layer and a soil layer from bottom to top, respectively; a water inlet tank is arranged at one side of the water inlet of the wetland device and connected with the water outlet of the water inlet tank through the branching pipeline; a mesh grille is arranged at the water outlet of the water inlet tank and used for removing large flotages and impurities in sewage and then injecting the sewage into the wetland device; and simultaneously, a flowmeter and a water inlet valve I are arranged on the branching pipeline between the water outlet of the water inlet tank and the water inlet of the wetland device; a water taking opening is formed on the branching pipeline which is communicated with the water outlet at the corresponding side of the water inlet of the wetland device; and a valve II is arranged between the branching pipeline and the water taking opening. The multi-medium constructed wetland water treatment system realizes quick switch between the single-stage wetland and the multi-stage wetland, effectively solves the fluctuation problem of the pollutant concentrations of the sewage, and also improves the adaptability of the wetland and widens the application range of the wetland.