Climate changes in the middle and lower reaches of the Yangtze River due to greenhouse effects in the 21st century are investigated based on the simulations both by some coupled atmosphere-ocean general circulation models (AOGCM) and a regional climate model (RegCM2). Assement of the models for their simulation to present climate in China show that they performs reasonably well. For example, the spatial correlation coefficients between simulated and observed mean annual surface air temperature can be 0.80℃ and 0.94℃ for the AOGCMs and the RCM; respectively. The AOGCM part is based on the average of the 5 AOGCM results provided by the Data Distribution Center of IPCC. It consists of 4 scenarios, which are greenhouse gas only, and greenhouse gas plus sulfate aerosol scenario of the IS92a, A2, and B2 of the SRES. The results show a general warming in the region in the future, like in the globe and in other parts of China. For example, in the end of the 21 st century in the region, the warming of 4.3℃ under GG and 3.1℃ under GS are simulated. Greater wanning is simulated in winter and spring than in summer and autumn. Similar temperature rise is simulated by the RCM. But both AOGCM and RCM simulated a weaker warming in the region when comparing with that in China and in the Globe. As for the precipitation change, under GG, an increase which is smaller than that averaged in China is simu-lated, while under GS it is a slightly decrease. The annual mean precipitation change simulated by the RCM shows similar increase. But differences are noticed when considering seasonal changes and the spatial distributions. Greater increase is found in winter (44%) and summer (23%) while the precipitation in spring and autumn will decrease, which is in the opposite direction to the AOGCM. The big increase of precipitation in summer may subsequently lead to more floods in the reason. A lot of uncertainties exist in assessing the climate impacts of greenhouse gas emissions. There are uncertainties in the emission scenario in the future and in the climate models, especially when concerning the aerosol effects, etc. The better performance of the RCM in simulating present climate refers that the climate change scenario simulated should be paid more attention, but still many work is needed for a more robust assessment of climate change in the region, as in the other places in China and in the Globe.