In order to explore the responses of soil nitrogen mineralization of common plant communities in the desert grassland of eastern Ningxia to soil drought, five plant communities, namely, Agropyron mongolicum, Artemisia scoparia, Medicago sativa, Caragana korshinskii and Artemisia ordosica were selected to investigate the changes in soil nitrogen mineralization of common plant communities under different soil water gradients (natural, saturated and drought). The results showed that soil moisture of different plant communities was 3.19%-5.17% in 0-20cm soil depth,while the average soil moisture content of each community in 0-200cm depth had all evident vertical dynamics, which were significantly higher than that of shallow soil layer, and its variation range was 10.89%-19.35%, and the sequence was as follows: Caragana korshinskii>Artemisia scoparia>Agropyron mongolicum>Agropyron mongolicum>Medicago sativa. Soil organic carbon content of Agropyron mongolicum was significantly higher than that of other communities and ranged from 3.505g/kg to 3.985g/kg. Soil total nitrogen content did not differ significantly between the community of Agropyron mongolicum, Artemisia scoparia, and Caragana korshinskii, and their value was 0.146-0.157g/kg, but higher than Artemisia ordosica and Medicago sativa. During soil nitrogen mineralization, soil nitrification of Artemisia ordosica, Caragana korshinskii and Medicago sativa community showed an increasing trend, and the difference increased with seasonal variation, whereas soil nitrogen mineralization of Agropyron mongolicum soil was characterized mineralization more stable, and the rate of soil nitrogen mineralization were relatively low. Compared to the positive response of soil nitrification action to soil drought in Caragana korshinskii and Artemisia ordosica community, the responses of soil nitrogen mineralization characteristics in Agropyron mongolicum Medicago sativa community was delayed. The main indices of soil nitrogen mineralisation were influenced by different nutrient factors. Under natural rainfall and drought conditions, soil nitrogen was positively correlated with soil moisture, total phosphorus and the nitrogen to phosphorus ratio, and negatively correlated with organic carbon and the carbon to nitrogen ratio. The changes of soil ammonium and nitrate nitrogen in each plant community weakened the correlations with other nutrient factors as persistent drought intensified, whereas soil nitrate nitrogen and microbial biomass nitrogen showed a significantly negative correlation after persistent drought and saturated moisture(P<0.05).