The invention discloses a carbon source self-supplying biogas production-type high-efficiency nitrogen removal horizontal subsurface flow constructed wetland. The horizontal subsurface flow constructed wetland comprises a bed body; the bed body is filled with a filler; wetland plants are planted in the filler; wherein a water inlet pipe and a water outlet pipe are respectively arranged on two sides of the bed body; the water inlet pipe communicates with a PVC (polyvinyl chloride) water distribution pipe 1 arranged on the upper part of the filler; the water outlet pipe communicates with a PVC water distribution pipe 2 arranged at the bottom of the filler; the water inlet pipe communicates with a water tank through a mixed-flow pump; at least one rake tooth-type guiding pipe is arranged at the lower part of the filler closed to the water inlet pipe; and each rake tooth-type guiding pipe communicates with a composite biological fermentation system outside the bed body. The wetland can notonly efficiently treat low C/N ratio sewage, but also realize in-situ resource-based disposal of wetland plants after harvest.