A comparative study on plant importance values and community diversity under different grazing systems was conducted in desert steppe of Inner Mongolia Plateau. The results showed that the importance values of Stipa breviflora

Cleistogenes songoriea

Allium polyrhizum and C. squarrosa were higher in the rotational grazing area and in closed area than in the free stocking area

while the importance values of annual plants were higher in the free stocking area. In year 2002

Shannon-Wiener index

Simpson index

and Pielou index were all found higher in the free stocking area than in the rotational grazing area. However

the distribution of importance values for the influential factors with these indexes was concentrated on several dominant and constructive species

which indicated that rotational grazed grassland was more stable than the free stocked one.