A field survey was carried out of the Weigan-Kuqa River Delta Oasis in South Xinjiang, collecting a total of 156 samples of topsoil (0~20cm) and subsoil (20~40cm) at 78 sampling sites laid out in the light of land use for analysis of soil organic matter (SOM) content and pH and their distributions, and variations of SOM in the topsoil and subsoil layers as affected by crop type, land use and soil pH. Results show that SOM varied in the range of 3.7~24.1gkg^-1 in content, and averaged 11.0 4.2gkg^-1 in the topsoil layer (0~20cm), and in the range of 2.7~12.9gkg^-1, and 7.0 2.2gkg^-1; in the sub-subsoil layer (20~40cm). The topsoil layer was much higher than the subsoil layer no matter in mean of SOM contents or standard deviation in soils under different types of crop and patterns of land use, with a variation coefficient being 20%~50%. Obviously the variation was at a moderate level. Variance analysis and stepwise regression analysis shows that the factors affecting SOM content also varied in effect. The integrated effect of the three factors, crop, land use and pH, could explain 45.1% of the variation of SOM content in the topsoil layer and 43.7% of that in the subsoil layer. Comprehensive analysis shows that crop type is the most important factor affecting SOM content in the study area.