Soil respiration impacts carbon sequestration rates and atmospheric carbon dioxide levels. Daily dynamics and seasonal dynamics in soil respiration rate in three types of fixed, semi\|fixed and mobile sand land were measured in 2005 to understand soil respiration properties and its relation with environmental factors in land desertification processes of Horqin Sand Land. The results showed that (1) daily fluctuations in soil respiration presented a single peak curve during spring and autumn and a double peak curve during summer in the three sand lands; (2) seasonal dynamics in soil respiration presented a double peak curve in all the three sand lands, with peak values occurring during the last ten\|days of June and August; (3) the daily range of soil respiration rate was significantly greater in fixed and semi\|fixed sandy lands than in mobile sandy land, and the seasonal range of soil respiration was fixed sandy land ＞semi\|fixed sandy land ＞ mobile sandy land; (4) soil respiration rate decreased significantly with increasing desertification, and the average rate of soil respiration in a growing season decreased form 2.32 mol CO2/(m2?s) in fixed sand land to 1.65 mol CO2/(m2?s) in semi\|fixed sand land and 1.06 mol CO2/(m2?s) in mobile sand land; (5) in all of the three sand lands, daily change in soil respiration had a positive correlation with soil temperature, and a negative correlation with air humidity; seasonal change in soil respiration had positive correlation with air humid, soil temperature and moisture, but the correlation was statistically significant only in the fixed sand land; (6) although changes in soil temperature, organic carbon and plant root carbon content were important factors affecting the soil respiration rate in land desertification processes, the primary factors dominating soil respiration were air humidity and soil moisture.