Soil organic carbon (SOC) in agricultural soils plays an important role for ensuring food security and mitigating global climate change. Thus, the past and potential effects of climate change on the SOC in agricultural soils have been widely noticed by global society. The net primary productivity (NPP), carbon input and SOC decomposition rate could be altered by changes of temperature, precipitation and CO_2 concentration due to the global climate change. Furthermore, carbon cycling could also be changed by the changes of land use and planting systems under climate change. The published data were used to illustrate the effects of global climate change on SOC in upland in China. It is estimated that the increase of temperature and precipitation ranged from 3.9 to 6.0℃ and from 9% to 11% in China until 2050s, respectively, and carbon input in agricultural system will be decreased by 2.3%-10% (average of wheat, maize and rice cropping systems). However, if consider the combined effects of increase of CO_2 concentration with global warming, carbon input will be increased by 13%-22% until 2050s compared with that before the period of 1990s. Model simulation results showed that until 2020s, 2050s and 2080s, SOC will be decreased by 2.7, 6.0 and 7.8 tC·hm~(-2) under CO_2 emission scenario, and be decreased by 2.9, 6.8 and 8.2 tC·hm~(-2) under high CO_2 emission scenario, respectively, which is ca. 4.5%, 10.5% and 12.7% of the SOC pool in 1980s. Furthermore, SOC pool will be decreased approximately by 10% at the end of the 21st century. If C inputs in agricultural systems are promoted with a 1% annual increase rate, there is a 100% increase in carbon input in agricultural soils by the end of the 21st century in China. An obvious uncertainty still remain whether the climate change will exert huge influence on soil carbon pool. The consensus that the positive and negative of soil carbon sequestration counteract to become carbon sink or source has not been reached. Thus, in the meanwhile of mitigating climate change and increasing soil carbon sequestration, there is a special need for predicting the carbon change in the future and quantifying the interaction between climate change and the feedback from organic carbon in agricultural soils.