Wetlands are the lands transitional between terrestrial and aquatic ecosystems. They provide humanity many services and commodities, are the habitats of wildlife, can control the water cycling and the biogeochemical cycling of nitrogen and carbon, and can filter and decompose the pollutants. The wetlands suffer loss and degradation because of reclamatio and human disturbance. Some theories, such as self-design versus design theory, succession theory, invasion theory, flood pulsing theory, edge effect theory, and intermediate disturbance hypothesis, can be used to direct the restoration of wetlands. Techniques of wetland restoration include to restore the natural hydrologic conditions, to rehabilitate suitable vegetation types, to control human disturbance, to meliorate the soil or landscape, to construct the buffer region, and so on.