Ecological engineering is a complicated engineering technology for sewage purification. It follows the principles of ecology. The sewage purification mechanism of constructed wetland was discussed firstly, then the new sewage purification methods using ecological engineering technology which appeared recently in domestic and abroad were summarized as follows: establish composite constructed wetland systems ，earthworm ecology filter ponds，bio-railings and biological floating island ，eco-gravel-bed technology as well as artificial plants purification technology . And finally, research direction and application of constructed wetland ecological engineering in the future were put forward.