The objective of this study was to examine the effects of increased nitrogen deposition and changing rainfall patterns on litter decomposition in a desert grassland.Our treatments included three different rainfall patterns (an ambient control, -30% and +30%) and addition of four different levels of nitrogen (an ambient control, 30, 50, and 100 kg hm^-2 a^-1).We used a litterbag method to investigate the litter decomposition process of three dominant species (Stipa breviflora, Artemisia frigida, and Cleistogenes songorica) and another common species (Kochia prostrata) in the context of changing nitrogen deposition levels and rainfall patterns in a desert grassland of Inner Mongolia.This study provides the basic data for research on response to climate change in the material cycle of desert grassland ecosystems.The results showed that:1) After 270 days of decomposition, the dry matter contents of S. breviflora, A. frigida, K. prostrata,and C. songorica were 69.95%-78.67%, 68.89%-79.89%, 64.68%-79.23%,and 66.89%-79.38%,respectively.The rank of the decomposition rate was K. prostrata > C. songorica > A. frigida > S. breviflora. 2)Nitrogen deposition and rainfall significantly affected the decomposition rates of S. breviflora and A. frigida(P < 0.05), but their interactive effects on litter decomposition rates were not significant(P > 0.05).Nitrogen deposition,rainfall,and their interactions significantly influenced the decomposition rates of C. songorica and K. prostrata(P < 0.05). 3)The addition of single moisture or nitrogen level increased the carbon and nitrogen contents of the microorganisms, and the interaction between moisture and nitrogen was more significant.4)The decomposition rate of litters was affected by biotic and abiotic factors.The correlation analysis showed that:A. frigida, C. songorica, and K. prostrata were significantly positively correlated with soil microbial carbon(P < 0.01); A. frigida, K. prostrata, and S. breviflora were significantly positively correlated with soil microbial nitrogen(P < 0.01); K. prostrata, and S. breviflora were significantly positively correlated with soil water content(P < 0.01); and A. frigida, K. prostrata, and S. breviflora were significantly positively correlated with above-ground biomass (P < 0.01).