With the rapid increase of global nitrogen deposition rate, it had a profound impact on the activity and metabolism of microbial community in the terrestrial ecosystem. Therefore, it is urgent to understand the response of soil microbial biomass and enzyme activity to nitrogen addition in the sensitive areas of global climate change. Therefore, taking Bayinbuluk alpine wetland in the arid region of the Central Asia as the research object, this study selected 3 types of well protected alpine wetlands:Swamp (S), Swamp meadow (SM) and Meadow (M), and arranged field in situ nitrogen addition experiments (nitrogen application concentrations are 0, 8 and 16 kg N hm^-2 a^-1, respectively). The aim is to explore the effects of short-term nitrogen addition on soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass carbon/nitrogen (MBC/MBN), microbial quotient (QMB), soil protease, urease, alkaline phosphatase, H₂O₂ enzyme and sucrase activities. Results showed that:(1) there were significant differences in soil microbial biomass and enzyme activities among different wetland types in alpine wetland. The MBC, MBN, MBC/N and QMB in the SM were higher than those in S and M. For enzyme activities, soil protease and alkaline phosphatase activities in the SM and M were higher, and H₂O₂ enzyme and urease activities in M were higher. (2) Nitrogen addition significantly increased soil MBC and MBN in the 3 wetland types, in which MBC increased by 7.00%-119.00% and MBN increased by 8.03%-38.26%. Nitrogen addition only significantly increased soil MBC/N and QMB in S and SM area (increased by 24.68%-113.10%), but inhibited soil MBC/N and QMB in M area (inhibited by 8.93%-10.36%). (3) Nitrogen addition significantly increased the activities of urease, protease and H₂O₂ in the soil of the 3 areas, by 7.25%-59.63%, 4.71%-58.55%, and 34.70%-157.27%, respectively. However, nitrogen addition had no significant effect on soil alkaline phosphatase activity. For sucrase, N1 treatment increased soil sucrase activity in the S area (increased by 58.58%), N2 treatment significantly decreased by 22.72%, while nitrogen addition had no significant effect on sucrase activity in SM and M area. (4) Results of structural equation model (SEM) showed that nitrogen addition directly increased soil microbial biomass and enzyme activity. With the change of wetland type (S-SM-M), soil enzyme activity increased significantly and indirectly through pH; Changes in wetland types also indirectly increased soil microbial biomass by affecting pH, organic carbon and available nutrients. In conclusion, nitrogen addition and wetland type can directly or indirectly affect soil microbial biomass and enzyme activity. Soil pH and organic carbon are the main influencing factors of microbial biomass and enzyme activity. This study can provide technical reference for the formulation of measures to deal with future climate change in alpine wetlands in arid areas of the Central Asia.