Abstract: In order to understand the characteristics of soil respiration(Rs)and its controlling factors in the young and mature forests of pine(Pinus yunnanensis)in Mopan Mountain National Forest Park of Yunnan province, we measured seasonal variations of Rs with Li-6400-09 chamber. The results were shown as follows: Rs fluctuated distinctly with seasonal patterns in the two sites. The rate of Rs in the mature forest(1.09-3.69 μmol/(m²·s))was significantly higher than that in the young forest(0.88-3.08μmol/(m²·s)). The contribution of soil moisture to Rs was significantly higher than that of soil temperature, which could be responsible for seasonal variation of Rs about 49.3%-79.4% in the young forest, and 63.3% -76.0% in the mature forest, respectively. The pH and soil nutrients had significant influences on Rs. The significant impacts of total P and pH on Rs were positive, and that of C/N was negative in two sites. Soil moisture had significantly positive relationship with total N and negative relationship with C/N in two sites, while the significant relationship between moisture content and soil total P as well as pH was only found in the mature pine forest. The results suggested that the severe drought in the southwest region led to the significant decrease of soil moisture, which may exert strong influence on Rs in the two sites. Moreover, soil moisture could have significant control on the spatial and temporal variation of Rs through its influence on soil permeability and soil nutrient in the young and mature pine forests.