Smooth cordgrass(Spartina alterniflora)is one of the most notorious invader plants and was listed in the alien invader species of China in 2003. The area of smooth cordgrass in Shanghai was about 3592 hm2. However, few information was available about its vegetative dispersal ability in the nature. In the present study, we surveyed the distribution in Shanghai and estimated the vegetative dispersal ability in Eastern End of Chongming Island, Shanghai. Strong vegetative growth was observed in individuals and patches of smooth cordgrass. After 9 months＇growth, smooth cordgrass individuals could develope 86 to 222 ramets per genet. The largest dispersal distance was 226 cm for individual smooth cordgrass. Mean dispersal distance of smooth cordgrass patches was 107 cm and the largest was 263 cm. At last, some strategies based on the observations had been proposed to control the rapid spreading of this species.