【英文摘要】Qianyanzhou planted forest is affected by typical mid-subtropical continental monsoon climate. It has plentiful water and heat resource but is in inconsistency of its seasonal distribution in the mid-subtropical region, thus seasonal drought frequently occur in this planted forest. Continuous measurement of carbon dioxide and water vapour exchange using the eddy covariance (EC) technique was made at the Qianyanzhou mid-subtropical planted forest as part of the ChinaFLUX network. The processes of carbon and water among soil-vegetation-atmosphere continuum were investigated synthetically by the EC technique combining with the sap flow, stable isotope and respiration measurements. The results showed that gross ecosystem photosynthesis (GEP), ecosystem respiration (RE) and net ecosystem production (NEP) showed clear seasonality, with low rates during droughts and in winter. Annual NEP varied among years from 306 to 430 g Cm?2 (mean 395, SD 50). Interannual variability in NEP was controlled primarily by air temperature and the ratio of precipitation and evapotranspiration that affected the RE/GEP ratio, which varied between 0.76 and 0.81 (mean 0.78, SD 0.02). Summer drought and heat wave were two aspects of weather that likely play an important part in the annual NEP of forest in this region. At the ecosystem scale, it was essential to consider how summer drought and heat wave conspire to affect short-term physiological and long-term ecological process, including photosynthesis and respiration processes. It will improve our understanding about the effects of seasonal drought on the coupling relationship between carbon and water cycles in this region. The obtained results will be used to model the change of carbon sink/source of China's mid-subtropical forest in future climate change, and to evaluate the role of planted forest in the carbon balance of the mid-subtropical region in China.