Abstract: Tarim River is the longest continental river in China, its watershed is the important base of grain and famous quality fruit in Xinjiang. There are the natural vegetation belts composed of arbors, shrubbery and grass along either banks of Tarim River. There are many problems of damaged ecosystem in the lower reaches of Tarim River in long time as a result of excessive fell, excessive herd and irrational exploitation and utilization of water resources in the middle reaches of Tarim River. The dominant factor is water to lead vegetation to damage. In this paper, by analysis on conditions of plant growth along the river and research on ecological response process of vegetable to change of groundwater in the middle and lower reaches of Tarim River, the converse succession of plant communities in the lower reaches of Tarim river is preaumed during recent 50 years and divide the different succession stages are divided. At first, the plant species, conditions of plant distribution, conditions of soil water and soil organic matter are investigated, then a lot of historical data about the lower reaches of Tarim River are collected and some work in succession of plant communities have been completed. By research and analysis, the succession series of plant communities in the lower reaches of Tarim river are：comm. Arbor ＋ shrub ＋ herbage→comm. Arbor ＋ shrub→comm. Arbor (or comm. shrub). On the basis of the response of the different plant communities to decline of groundwater, the sequence of degraded plants is：the stage of degraded herbage→the stage of degraded shrub→the stage of degraded arbor. The structure and composing of plant community change obviously during the converse succession. At different sections in the lower reaches of Tarim River, the actualities of degraded plant are unlike. There are different status of plant growth to decline of groundwater at different sections in the lower reaches of Tarim river such as Yinsu, Abidali, Alagan and Kaogan section etc.

Key words: converse succession, structure of plant community, lower reaches of Trim river