As an emerging concept, small wetlands obtain increasing global attention from scholars to policy-makers. Small wetlands provide the essential ecosystem services despite of their limited areas. Focusing on small wetlands can not only expand the research scale, but also promote the development of wetland research discipline. This paper introduced the background of small wetlands studies, generalized the definition and classification of small wetlands, and then concluded their cumulative impacts and landscape characteristics. Next the paper reviewed the varies and valuable ecological services provided by small wetlands, including maintaining critical habitats, providing migrating stepping stones, regulating hydrologic process, purifying contaminated water, and creasing pleasant urban and rural landscape. As a conclusion, we suggested that research on ecological process and function mechanism of small wetlands should be further strengthened in the future. Additionally, the construction and restoration programs of small wetlands should be integrated with current wetland conservation schemes and rural-urban ecological construction programs to promote their sustainable development.