In 2011~2014,the field experiment with different fertilizer treatments was conducted in the Stipa brevifloradesert steppe of Inner Mongolia.The LI-8100 was used to investigate seasonal variations of soil respiration rate,and combined with soil nutrients,underground biomass and environmental factors to analyze the relationships between soil respiration rate and impact factors.The results showed:1)The seasonal variations of soil respiration were emerged unimodal curve,and the peak occurred in August.There were not affected by fertilization2)The soil respiration was exponential correlation with temperature and precipitation,and its interannual variations were affected by precipitation3)N,P and NP fertilizer all could promote soil respiration in growing season,but the effect degree depends on precipitation.The higher the precipitation is,the better the effect will be4)With the increased N fertilizer,the soil respiration rate was enhanced,but the correlation between soil respiration and environmental factors was weakened.The changes of soil respiration rate in P and NP fertilizer treatments were greater than that in N fertilizer treatment,and the seasonal average soil respiration rate were highest in P fertilizer,and second in NP fertilizer.