Abstract: The experiment was conducted with Halaxylon ammodendron, Tamarix ramosissma Ledeb, and Picea schrenkiana woodland ecosystems as the subject monitored in Sangong River Basin in Xinjiang, and their soil CO2 emission characteristics are studied comparatively. The results showed that: 1) the diurnal variation of soil respiration rate in H. ammodendron forest during August is a bimodal curve, while it is unimodal curve in June and October. Daily soil CO2 emission in H. ammodendron forest in a descending order was August (4.34g/(m2·d))>June (1.86g/(m2·d)) >October (1.17g/(m2·d)). Soil respiration rate was higher in the day than that in the night in both June and October but quite the reverse in August. 2) Daily soil CO2 emission in different forests in a descending order was P. schrenkiana forest (21.71g/(m2·d))>H. ammodendron forest (4.34g/(m2·d)) > T. ramosissma Ledeb forest (1.84g/(m2·d)) in August. The both curves of soil respiration rate of P. schrenkiana schrenkiana forest and T. ramosissma Ledeb forest were unimodal curves, which were different from of bimodal curve of H. ammodendron forest. The soil respiration rate in both P. schrenkiana forest and T. ramosissma Ledeb forest were higher in day than that in night, but quite the reverse in H. ammodendron forest. 3) Soil CO2 emission rate has significant positive correlation with soil temperature in P. schrenkiana forest, while soil CO2 emission rate has significant positive correlation with air relative humidity in H. ammodendron forest.