Spartina alterniflora Loisel was used to protect slopes in sea wall engineering, which replaced the traditional protection model of sea wall by large area of claybank. Because the stems can prevent sea wave and the root systems can strengthen the dyke, significant effects was got on slowing the current, eliminating the sea wave and immobilizing the soil. As an important component of blow - fill-construct sea wall engineering, erosion of tide and stormy waves on sea wall water-meeting slope was effectively prevented or alleviated and safety of sea wall was guaranteel by using Spartina alterniflora to protect slopes. Significant engineering, economical and ecological benefits were obtained.