Abstract: Investigation on plant component structure in 3 different sizes islands of Kunes river in Xinjiang was carried out. The Investigation concluded that there were 63 species of plants belonging to 27 families and 61 genera, and there were 8, 29 and 52 kinds of plants in small, medium and large islands respectively. The number of common species were different in the three islands, it has 19 common species in large and medium islands, it also was the largest number. The maintypes of plant ecotype were the erect growth forms, erect root forms, the grophytes and the mesphytes. These conclusions revealed that the number of plant species was related to the size of islands, the number of plant species increased with the increase of islands area. The distribution pattern of plant species in these islands were nested subset structure. The sturcture of plant growth forms and life forms showed that the plant communities have the plant and root characteristics of herbaceous plant communities in themedtemperate zone and also has the typical climatic characteristics of undergroundbud plants, it could not withstand flooding.