Abstract:The niche breadths and niche overlaps of 12 main plant populations grown on the gradients of soil water, soil salt and soil organic content in Leymus chinensis grassland for grazing were measured using the formulas described by Shannon-Wiener and Pianka. The results show the niche breadths of Leymus chinensis, which were greater than other species, were 0.910, 0.869 and 0. 930 on the gradients of soil water, soil salt and soil organic respectively. The niche breadths of Lathyrus quinquenervius, Heleochalis intevsita and Phragmites communities were much narrower. Chloris virgata, which is one of the pioneer plant of grazing succession, had much greater niche breadths (average on the three gradients 0.707) than the other two species (Suaeda corniculata, Puccinellia tenuiflora ). The niche overlaps between the species with broad niche breadth and other species were much greater. The niche overlaps among the species distributed in the same/adjacent grazing stages or the species which have the same/similar environment requirements were great. Under grazing condition, the process of community succession was the one of species’ niche separate.