Spartina alterniflora Loisel is a native plant along the Atlantic and Gulf coasts in America. With its high productivity, propagation, tolerance, dense and vigorous belowground parts, this species colonizes new mudflats, forms a monoculture in introduced areas, and shows strong invasion potential, thus has negative ecological effects. This study aims to synthesize information on the positive and negative effects of S.alterniflora. Information on naturalization trends of this species is available from Willapa Bay, USA, with an introduction history of more than 100 years, in the San Francisco Bay, USA (introduction history of nearly 40 y), and on Chinese coasts (introduction history of >30 y). There are also positive effects: protecting the seashore from storms, modifying the landscape of mudflats; accelerating land formation, changing the hydrological regime of estuaries; fixing carbon, decreasing the release of greenhouse gasses; providing habitat and nutrients for some species. However, invsion by this plant also threatens regional biodiversity. S.alterniflora should be managed considering the possible benefits. For example, in some coastal regions with serious erosion, the eradication of this exotic should proceed prudently. In shoreline areas with higher sedimentation rate, and in polder reclamation areas, ways of utilisation would be an effective method. Using the vast biomass of this plant as new food source, health products, and biogas could limit its spreading and propagation, and such an ecological engineering could benefit both natural biodiversity and local people′s income.