The invention provides a sewage treatment method of a vertical current mangrove forest constructed wetland ecosystem. The sewage treatment method comprises the following steps of: A, establishing a constructed wetland; B, paving a water inlet pipe on the surface layer of the constructed wetland flatly, wherein a plurality of holes are distributed at two sides of the bottom of the water inlet pipe; C, paving gravels at the bottom of a constructed wetland bed body, paving broken stones on the gravels, paving oyster shells on the broken stones, paving a PVC (Poly Vinyl Chloride) flexible plate with meshes on the oyster shells, paving mangrove forest planting soil on the flexible plate for plating mangrove plants; D, filling oyster shells in a water inlet region, artificially stocking large benthonic animals on the mangrove forest planting soil layer; and E, every other 8-15 years, completely felling the mangrove plants, and re-planting the mangrove plants. According to the invention, the mangrove plants as perennial woody plants are used as the plants in the constructed wetland, thus the problem that the plants in the wetland need to be harvested every year is saved, and a large quantity of manpower and material resources are saved.