Potential blooms and red tide in river and sea may be caused by coastal aquaculture wastewater inestuarine and coastal areas. In this study, a type of ecological and efficient constructed wetlands was launched to purify coastal aquaculture wastewater. Optimal salt tolerant content was confirmed at different salt concentration in influent by constructed wetland treatments. The mechanism was indicated by removal efficiency, microorganism quantity, microbial metabolism function and microbial community diversity. The results showed that:Coastal aquaculture wastewater was purified efficiently by constructed wetlands, and the quality of effluent reached class Ⅲ of surface water quality standard (GB 3838-2002); The optimal salt tolerant content was 1% at the different initiating salinity in influent, and the improved performance of contaminants removal was obvious (P<0.05) with 93.3% of organic matters removal and 77.12% of ammonia removal in effluent. The main removal path of coastal aquaculture wastewater in constructed wetlands is nitrification-denitrification, and nitrification/denitrification bacteria can work normally under the stress of 1% salinity. The utilization of carbon source by microorganisms tended to diversify under the influence of salinity. As a result, constructed wetland can be used as a green option for coastal aquaculture wastewater to solve or relieve the potential eutrophication.