The social impact of global climate change is currently one of the important fields of global change research. Studying the historical climate change and its social impact from historical perspective could provide the valuable references for current human response to the global warming. Based on the previous studies, the climate changes in the world and in China during the North Song dynasty were summed up. The study results pointed out that the climate during the North Song dynasty changed from warm in the early stage to cold and dry in the late stage because of the unique natural environment in China ,which just lied between the turning period of the late Tang dynasty and the little ice age of Ming and Qing dynasties. The obvious climate fluctuation and the great change rate of precipitation caused the higher frequency of flood disaster during the North Song dynasty,which has caused the great influence on agriculture production, social and economic development. The study results have very important implications to understanding the past climate change and its impact.