The increase of global nitrogen deposition has changed the nitrogen (N) cycle process of grassland ecosystems, and the resulting ecological effects have become the focus of current research. In this paper, the grassland with short-term enclosure years around Urumqi was taken as the research object. The soil enzyme activity and microbial composition of free grazing land and the enclosed grassland were analyzed by simulated nitrogen deposition experiment. Combined with soil nutrient and stoichiometric characteristics, the effects of nitrogen deposition on soil microbial composition and soil enzyme activity of short-term enclosed grassland were discussed, which provided theoretical basis for the protection, restoration and management of grazing grassland in this area. The results showed that: (1) the contents of soil organic carbon (SOC), soil total nitrogen (TN) and soil total phosphorus (TP) were generally increased with the increase of enclosure years, indicating that enclosure was beneficial to the improvement of soil nutrient content. Compared with the average value of grassland in China, the soil carbon/nitrogen (C/N) in this grassland was relatively high, and the soil carbon/phosphorus (C/P) and soil nitrogen/phosphorus (N/P) were relatively low, indicating that the decomposition of soil organic matter in this grassland was good, and was conducive to the release of soil carbon and phosphorus, while the soil nitrogen was relatively short. (2) The number of fungi in 5-20cm soil layer of the 3-year enclosed grassland was higher than that in other plots. The activities of sucrase and catalase were the highest in the surface soil of the enclosed grassland for 3 years; The number of actinomyces was the highest in the 7 years after enclosure, which indicated that enclosure could promote the growth of soil microorganisms and the improvement of soil enzyme activities. (3) Nitrogen addition inhibited soil fungi, and N5 and N10 treatments significantly increased the number of soil bacteria in various plots. Nitrogen addition had no significant effect on actinomyces in 0-10cm layer of grassland enclosed for 7 years, while nitrogen deposition significantly increased the number of actinomyces in 5-20cm layer of other plots, among which N5 and N10 treatments had the most obvious promoting effect; nitrogen addition could promote the activities of urease, sucrase and catalase in the soil of the grassland, and N5 and N10 treatments had the most obvious effect. Comprehensive analysis showed that nitrogen deposition could directly or indirectly affect soil microorganisms and enzyme activities. As a means of grassland management, the short-term enclosure had a certain effect on the restoration of the degraded grassland ecosystem, and could accelerate the restoration of the degraded grassland by improving soil physical and chemical properties, adjusting nutrient content and stoichiometric ratio.