Climate and soil nutrient change are important factors for plant phenological phase change in natural ecosystem.The objective of this work were to study the effect of climate warming and higher soil nitrogen on the DNA methylation level and pattern of Stipa breviflora.A experiment was conducted in the western desert steppe of Inner Mongolia.The methylated MSAP analysis of Stipa brevifora at different florescence was performed by capillary electrophoresis under the artificial simulation of temperature increasing and nitrogen increasing conditions.The results showed that the total number of Stipa breviflora sample amplification bands was 5049,the average total methylation level was 68.39%,total methylation level were higher than half methylation.With the development of flower,the total methylation level presents the tendency declining at the beginning and rising up in late.The total methylation level was decreased by 1.75% in the early stage under warming treatment,and 4.76% in the later stage under nitrogen treatment.The methylation pattern analysis showed that both demethylation and methylation variation occurred at the CCGG locus and there were spatial and temporal differences.These results may have theoretical foundation use for the further study to find flowering related genes which induced under climate change condition.