Through analysis of the evolvement of major conclusions and methods for impacts and adaptation on climate change in the IPCC WGII five assessment reports, the causes and their impacts on international adaptation negotiations and domestic adaptation policies were studied. It points out that because of the rapid increase of literature, sophistication of methods and tools for evaluation and adaptation, increasing concerns and more emphasis on adaptation, IPCC further confirms that climate change has had and will have extensive and profound impacts on natural and human systems; future social-economic pathways, adaptation and mitigation, and risk governance at different levels will affect climate-related risks. IPCC assessment reports promote the formation and implementation of adaptation policies both at the international and national levels. Although China has merged adaptation into related domestic policies, still there are problems in cognition, capacity, mechanisms and institutions. More efforts are needed to enhance national and local adaption efforts.