Climate change is disturbing the mutual adaptive balance between human beings and surrounding ecosystem. Whether positive and/or negative, climate change effects on the ecosystem and social economic system are both direct and indirect. In this paper, the science background is simply summarized about the climate change. Change and its effect factors are discussed. By analyzed the key effect factors which could cause the climate change and the anthropogenic influence upon climate change, it will be help for us to understand the present climate change. Also, the key fields and the important strategy measures for climate change effect assessment are proposed.