To determine impacts of soil temperature and soil moisture regimes on soil respiration, daily and annual variation patterns of total soil respiration rate and its components, i.e. soil microbial respiration rate, soil root system respiration rate, and litter respiration rate in rubber plantations, 4 a, 12 a and 19 a old separately, were investigated with a Li-6400 portable photosynthesis system. Results show that during a day of observation, the appearance of peak and valley of soil respiration rate varied sharply from plantation to plantation different in age. However, the values obtained between 9:00 and 11:00 were all quite close to the daily mean values of soil respiration.. Although daily variations of the components differed in extent with age of the plantation, the component of litter respiration rate was the lowest in any case. Obvious monthly variations of soil respiration were found in rubber plantations, 4 a, 12 a and 19 a old, with the mean rate being 2.45, 2.63 and 2.96 μmol m^-2 s^-1, respectively, and the maximum value recorded in July or August and the minimum in February or March. No significant difference was observed in monthly variation of soil respiration between rubber plantations different in age. Soil microbial respiration accounted for 43.6% of the total soil respiration, being the highest, and was followed by root system respiration (36.1%) and litter respiration (20.4%). A remarkable exponential relationship was found between soil respiration rate and soil temperature, but not so as such was between soil respiration rate and soil moisture. It is, therefore, concluded that soil respiration is closely related to soil temperature, but may not be directly related to soil moisture in rubber plantations in Hainan.