There is a wide agreement in the international scientific society that climate change will modify climatic variables. Atmosphere-Ocean General Circulation Model (AOGCM) is an appropriate model to produce climatic scenarios. The first step to climate change studies is currently using the most appropriate AOGCM output. In this study, AOGCM's for a time period of 1961-1990 in Shahrekord synoptic station are therefore compared and finally the best AOGCM is presented. The employed models in the paper include CCSR, CGCM2, CSIRO and HADCM3 which was mentioned in the Third Assessment Reports of IPCC. The results display that the HADCM3 output has more appropriate correlation than the other models comparing with the observed data of the station. According to the evaluation of climatic scenarios, climate change has the unfavourable impacts on hydrology and water resources of the basin, thus these results are suitable ones of the most achievements to study climate change effects on stream flow changes and variability in Northern Karoon region, Iran.