In 2012, a field experiment with different fertilizer treatments was conducted in the Stipa breviflora desert steppe of Inner Mongolia. The LI-8100 was used to investigate daily and seasonal variations of soil respiration rate, and the relationships between soil respiration rate and environmental factors were analyzed. The results showed that: 1) In the rapidly growing stage (August), the respiration rate in 10 g N x m(-2) was significantly higher than in the other treatments. No significant differences were observed among 5 g N x m(-2), 2.5 g N x m(-2) and CK. 2) During the early and middle growing stage (May to September), P fertilizer improved the soil respiration rate. 3) Fertilization did not change the daily and seasonal variations of soil respiration. The daily variations of soil respiration of all fertilization treatments were almost the same, with the highest values occurring within 10:00-14:00 and the lowest values occurring within 03:00-05:00. The peak of seasonal variation occurred in August. 4) The soil respiration rate was significantly related to soil temperature at 5 cm depth and soil moisture at 0-10 cm depth, and the determined coefficients were 0.40-0.58 and 0.51-0.70, respectively, indicating that soil moisture was the major factor affecting soil respiration.