[Objective] Based on the 4 years old, 20 years old Eucalyptus sp. plantations and 22 years old Pinus massoniana plantations in Yaoshan Mountain in Guilin City of Guangxi Zhuang Autonomous Region, this study conducted the characteristics of forest soil respiration which droved by forest types, forest age and other factors, so that to provide basic data with carbon dynamic simulation on Eucalyptus and Pinus massoniana plantations ecosystem.[Methods] From March to August in 2013(during Spring and Summer), the soil respiration and its components(soil autotrophic respiration and soil heterotrophic respiration), soil temperature and the soil water content of the three forests were observed monthly with the Li-8100 automated soil CO₂ flux system respectively.[Results] (1) There was no significant difference in the soil respiration rate among the three forests; (2) The autotrophic respiration rate of the 4 years old Eucalyptus sp. forest was higher than that of the 20 years old Eucalyptus sp. forest and 22 years old Pinus massoniana forest. The heterotrophic respiration rate of the 20 years old Eucalyptus sp. forest was higher than the 4 years old Eucalyptus sp. forest and the 22 years old Pinus massoniana forest; (3) According to the correlation coefficient analysis, soil temperature was the main environmental factor influencing the soil respiration rate and its components. There existed exponential relationships between soil temperature and soil respiration rate and its components; (4) In the 4 years old Eucalyptus sp. forest, the correlation between soil moisture content and soil respiration rate was indistinctive, there were significant positive correlations between soil respiration rate and soil moisture content in the 20 years old Eucalyptus sp. forest, and significant negative correlations between soil respiration rate and soil moisture content in the 22 years old Pinus massoniana forest; (5) the Q₁₀ value analysis of the temperature sensibility coefficient of the three forests indicated that the value of the 4 years old Eucalyptus sp. forest was higher, the 20 years old Eucalyptus sp. forest and the 22 years old Pinus massoniana forest were lower.