【Objective】 Soil extracellular enzymes, as the catalysts of soil biochemical reactions, directly drive soil element cycling and energy flow processes and play indispensable roles in the biogeochemical cycling of carbon, nitrogen, and phosphorus in desert ecosystems. Winter snow is a key climatic factor regulating soil element cycling. Soil extracellular enzyme activities respond sensitively to the changes in winter snow cover and the relatively stable hydrothermal conditions highly alter soil extracellular enzyme activities under the winter snow cover. Thus, changes in the winter snow cover will trigger fluctuations in soil extracellular enzyme activities, significantly influencing the nutrient cycling processes in desert ecosystems which are water-scarce and nutrient-poor.【Method】 In order to investigate the effects of winter snow cover changes and arbuscular mycorrhiza (AM) fungi on soil enzyme activities in the Gurbantunggut Desert under the background of a “warm and humid” trend, we conducted a long-term field experiment simulating winter snow cover changes and in situ inhibition of AM fungal activities with a split-area randomized block experimental design. The following treatments were adopted; for the primary zone, the control (40 mm water increase, W) and an AM-inhibition treatment (40 mm water increase with the addition of benomyl, BW); for the subplot zone, including three levels, 100 % snow cover increase (+S), natural snowfall (CK), and 100 % snow cover decrease (-S). Soil samples were collected from 0-10 and 10-20 cm soil layers, soil physicochemical properties, and soil enzyme activities which are related to soil carbon, nitrogen, and phosphorus cycling were determined to uncover the effects of AM fungi on soil enzyme activities and microbial metabolism limitation under the background of winter snow cover changes in the desert ecosystem.【Result】 (1) AM fungi significantly increased the aboveground net primary productivity of plant community, decreased the content of soil available phosphorus and ammonium nitrogen, but increased the content of soil organic carbon. The activities of soil enzymes related to soil carbon, nitrogen, and phosphorus cyclings were decreased under the natural snow cover and increased snow cover in the AM fungi treatments. In contrast, AM fungi treatments increased the activities of soil enzymes which are related to the soil carbon and nitrogen cyclings under decreased snow cover. (2) Based on the vector analyses, our results indicated that soil microbial activities were co-limited by soil carbon and phosphorus in desert ecosystems. Furthermore, we found that AM fungi decreased soil microbial carbon limitation under the natural snow cover and increased snow cover treatments, but there was no consistent pattern in the effects of AM fungi on soil microbial carbon and phosphorus limitation under the decreased snow cover treatment.【Conclusion】 AM fungi play an important role in promoting plant available phosphorus and ammonium nitrogen uptake, enhance soil enzyme activities which are related to soil carbon and nitrogen cyclings, and alleviate soil microbial carbon limitation in desert soils under the background of winter snow cover changes. Importantly, our results revealed the effects of winter snow cover changes and AM fungi on soil extracellular enzyme activities and soil microbial metabolism limitation. This contribution will provide a reference in the understanding of belowground ecological processes and feedbacks, and a scientific basis for the protection and ecological restoration constructions for desert ecosystems in the future.