Abstract: The potential vegetation, as a final state of succession which achieves the balance with its site, is the most stable and mature climax vegetation type at the site without human interference. The ecological and environmental problems of the northwest arid area are very serious. Taking the potential vegetation as the reference for showing backgrounds of vegetation and rules of change has become the preliminary and infrastructural work towards ecological construction in arid areas of Northwest China. Based on the integrated sequence classification (IOCSG) and the support of GIS, this paper simulates distribution of vegetation, and analyzes dynamic changes in the study area. 1) Using the IOCSG model in arid areas of Northwest China, the accuracy of potential vegetation simulated reached 78%. 2) There were 21 potential vegetation types distributed in the study area. The diversity of vegetation in different regions was quite different. Vegetation was abundant in Tianshan, Altai, Daxinganling. In contrast, in the Junggar Basin, Tarim Basin, and Badain Jaran desert, the distribution of vegetation was relatively simple, mainly in desert and semi-desert. 3) As climate and environment change at a site, the regional vegetation system shows instability. There are four typical variation patterns, i.e. increasing change, reducing change and disappearing and fluctuating vegetation. 4) Complicated processes of succession of the potential vegetation happened because of changes in climatic and environmental adaptability at the site. In Tianshan, Altai, Daxinganling, to the west of Daxinganling and Hulunbeier, successions of the potential vegetation are more significant.