Five parallel transects (1m×40m-1m×70m) placed 50m apart, were sampled at the altitude of 4000m from south-slope to north-slope in Songpan county which lies in the eastern edge of the Qinghai-Tibet Plateau. During 2004-2005, all 251 quadrats (1m×1m) were investigated in terms of plant community composition, physicochemical characteristics of soil, and depth of winter snow-cover. The functional module TWINSPAN of software PC-ORD was used to classify the plant communities, based on relative frequency as the community index, and an environmental index comprising depths of snow-cover, soil and organic matter, soil moisture (0.25mm and 2mm）, total P, total K, NH+4-N, hydrolytic acid, pH, slope etc.. CCA was then used to classify plant communities. The results show four community types from south-slope to north-slope: Potentilla -Ajania alpine shrub meadow, Ptilagrostis-Carex alpine meadow, Salix-Carex-Ptilagrostis alpine shrub meadow, and Rhododendron alpine shrub. From south-slope to north-slope, herb cover decreased from 75% to 39%, and shrub cover increased from 25% to 54%. And around the mountain ridge (about 50m) the type of vegetation in south-slope and north-slope shows significant differences. In the winter of 2005, the average snow depth on the south-slope was 21cm, compared to 26cm on the mountain ridge and 34cm on the north-slope. Snow depth was positively correlated with shrub cover (r =+0.40, p<0.01, n=248), but negatively correlated with herb cover (r=-0.45, p<0.01, n=248). ANOVA indicated that soil depth, soil moisture, pH, soil organic matter and total P differed between north and south slopes, tending to increase from south-slope to north-slope, and significantly correlated with the average snow depth (r=0267, 0.286, 0.199 and -0.183, respectively, p<0.05, n=119); soil total K and NH+4-N showed no significant differences with aspect, and no significant correlation with average snow depth (r=-0.068 and 0.104, respectively; p>0.05, n=119). This suggests a complex interaction between aspect, snow depth, and a variety of soil characteristics. The CCA order of community, as well as the correlation analysis of compositor axis and environment index also showed that slope, snow-cover thickness, soil organic matter and soil moisture were the primary factors that induced the different plant community types in south-slope and north-slope, while the impact of soil NH+4-N and total K were not significant.