Soil microbial biomass plays a critical role in soil nutrient cycling and is sensitive to atmospheric nitrogen deposition, rainfall change pattern and global warming. However, the effects on soil microbial biomass,especially seasonal one,are still unclear. Therefore,a field multiple-factor experiment including precipitation increase,nitrogen addition and temperature increase was conducted in the Gurbantunggut Desert in September 2014 so as to understand the effects of atmospheric nitrogen deposition,precipitation and global warming on soil microbial biomass carbon(MBC) and nitrogen(MBN) in different seasons in temperate desert ecosystem. It was found that there were no seasonal differences in the responses of soil MBC and MBN and the ratio of MBC to MBN and simulated rainfall. The soil MBC and MBN and the ratio of MBC to MBN were positively correlated with nitrogen addition,and the high nitrogen in autumn 2015 affected significantly the MBC and MBN and the ratio of MBC to MBN. The temperature increase in autumn 2015 and spring 2016 decreased the soil MBC and MBN and the ratio of MBC to MBN,but increased significantly these in summer 2016. The precipitation and nitrogen increase affected interactively the seasonal soil MBC and MBN and the ratio of MBC to MBN,but the effects of interaction of nitrogen,precipitation and temperature increase on the seasonal soil MBC and MBN and the ratio of MBC to MBN were not significant. Owing to the ratio of MBC to MBN ranged from 1.52 to 4.34,our results suggested that bacteria were dominant in soil microbial community in the Gurbantunggut Desert.