Abstract: Based on the 12 habitat factors and the importance value of 48 plant species surveyed, the relationships between environmental factors and vegetation patterns in the semiarid desertification area were explored. A research area of Agula Ecohydrological Experimental Station which is located in the southern Horqin Sandy Land in China was selected to set up 19 plots along three lines of longitude. The types of plant community, the plant of main families and the plant of different lifeforms in this region were investigated in relation to environmental factors using MRT and DCCA. In order to eliminate redundant environmental variables, the environmental factors which significantly influ〖HJ*3〗ence plant community composition were chosen by forward selection and Monte Carlo tests. Results showed that: 1) The plant communities in this region could be divided into 4 types by MRT, which was in accordance with the spreaddimensional pattern on the DCCA ordination diagram. The four associations were Setaria viridis + Agriophyllum squarrosum-Artemisia halodendron association, A. sieversiana + Medicago ruthenica + Leymus chinensis association, Polygonum divaricatum-Hedysarum fruticosum + Caragana microphylla association, Juncus amplifolius+ Phragmites australis association; 2) Results of DCCA ordination indicated that Compositae and grasses were distributed in four communities in the study area, while legumes were more likely to be found in the better fixed dunes. With the improvement in the level of fixed dunes, the evolutionary process of the life forms about species was: the annual herb→ the annual and perennial herb→ the annual and perennial herb + shrubs, subshrub →the annual and perennial herb; 3) Four environmental variables were used in the species-environment correlation analysis. The first axis indicated that the dune community and the meadow community were discontinuously distributed, and the electrical conductivity and clay content of soil were important factors, while the second axis reflected that the soil organic matter and the capillary rise of water content play a decisive role in the community distribution of sand dunes under different fixed level status.