NOVELTY - The sewage treatment device comprises three sections of filler arranged with a vent pipe. Height of an artificial wetland bed is higher than that of a double-walled guardrail (23) provided with an organic matter. A top part of the double-walled guardrail is sealed and connected with a water inlet pipe (2). An end of the water inlet pipe is open or closed state. The top part of the guardrail is provided with a gas-guide tube connected with a water tank. The water tank is connected to an artificial wetland provided with a water distribution pipe (15).    USE - Used as sewage treatment device.    ADVANTAGE - The sewage treatment device is simple to operate at low temperature, stable and cost-effective, and has good heat preservation effect.    DETAILED DESCRIPTION - The sewage treatment device comprises three sections of filler arranged with a vent pipe. Height of an artificial wetland bed is higher than that of a double-walled guardrail (23) provided with an organic matter. A top part of the double-walled guardrail is sealed and connected with a water inlet pipe (2). An end of the water inlet pipe is open or closed state. The top part of the double-walled guardrail is provided with a gas-guide tube connected with a water tank. The water tank is connected to an artificial wetland provided with a water distribution pipe (15) on a top part of the third section. A bottom part of the third section is provided with a water collecting pipe. Height of a water outlet of the water collecting pipe is higher than that of the artificial wetland bed. The second section is connected with a water outlet pipe (9). Height of the water outlet pipe is higher than that of the artificial wetland bed. The water distribution, the water inlet and the water outlet pipes are connected with a top part of the water tank through a water inlet valve. The water outlet of the water distribution pipe is connected with an ice layer (21) to form an air insulating layer. The air insulating layer is connected to a middle part of the water outlet of the water distribution pipe. Total length of the three sections is matched with 10-20% of length of the water inlet pipe. Length of the second section is above 70-85% of total length of the first and the third sections. The filler is filled the three sections at a height of 1.6-1.8 m or 2.2-2.5 mm. The third section has a grain diameter of 16-32 mm. The second section has a grain diameter of 8-16 mm. The water inlet valve and the water outlet pipe are provided with a main control valve and a sub-control valve with different heights. The water collecting pipe and the water outlet pipe are provided with three branched or sub control valves. The three sub control values are in a bottom part of the artificial wetland bed. The water distribution pipe uniformly distributes water to a hole with a diameter of 3 cm. The water collecting pipe is provided with a water collecting hole with a diameter of 5-10 cm and multi-hole with a diameter of 1-3 cm. The bottom part of the double-walled guide rail is paved with an anti seepage layer.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a sewage treatment device.    Water inlet pipe (2)    Water outlet pipe (9)    Water distribution pipe (15)    Ice layer (21)    Double-walled guardrail. (23)