Grazing is one of the most important anthropogenic activities in drylands, which could influence the structure and components of soil microbial community. It is critical to understand the effects of grazing on metabolic characteristics of fungi community that is closely related with nutrient cycling and ecosystem stability in drylands. We selected three levels of grazing intensity: heavy grazing (HG), moderate grazing (MG) and light grazing (LG). We set five diameter classes of trees \[A (0-10 cm), B (10-20 cm), C (20-30 cm), D (30-40 cm) and E (>40 cm)\] with each grazing level in Ejina Oasis to explore metabolic characteristics and diversity of rhizospheric fungi community in Populus euphratica Oliv. forest by BiologFF microplate. Theresults showed that diameter class size had significant effect on fungi community metabolism, accounting for 7.8% of variance. The fungi community metabolic activities gradually decreasedalong with increasing grazing intensity (AWCD_LG>AWCD_MG>AWCD_HG). There was no obvious difference under different diameter classes in LG site while significant differences were observed in MG and HG site. This result indicated that the effects of grazing intensity on P. euphratica were dependent on tree diameters, thus leading to diverse responses of fungi community. While there was no interactive effect between grazing intensity and diameter on metabolic activities of fungi community but they interacted to affect diversity, indicating that grazing intensity didn’t change the metabolic intensity of fungi community but changed the community structure. In addition, the effects of grazing intensity and diameter class of trees on fungi community metabolic characteristics were mainly due to alteration of fungi principally using the small molecular carbon sources.