Combining qualitative study and quantitative study, this article analyzes the reasons why U.S. president Trump decided to withdraw from the Paris Agreement, assesses the impact of U.S. withdrawal from the Paris Agreement on the implementation of the Paris Agreement and China, and makes policy suggestions on how China should respond. Undoubtedly, U.S. withdrawal is a big event for global climate governance in the sense that it will exert multi-dimensional impacts on the implementation of the Paris Agreement. U.S. withdrawal seriously undermines the universality of the Paris Agreement, which is perceived as the backbone of global climate regime, aggravates the leadership deficit in global climate governance, sets a bad precedent for global climate cooperation, wins itself more emission right and lower cost of mitigation while squeezing other countries' carbon emission space and raising their cost of mitigation, make it more difficult for developing countries to mitigate and adapt to climate change, may cost the world the window of opportunity in climate mitigation, will compromise the quality of future IPCC reports and ultimately undermine the authority of future negotiations under the Paris Agreement, and finally makes the long term goal much tougher to achieve, even unlikely. In general, the framework of global climate governance will not collapse but will be shaken; the process of global climate governance will not be reversed but will be slowed. U.S. withdrawal poses a lot of challenges to China. One of them is the rising demand and pressure from international community that China should assume global climate leadership alone. In this context, China should achieve the most ambitious targets in the range of its Nationally Determined Contribution(NDC)domestically, and facilitates the reestablishment of shared global climate leadership, which means shifting from G2 to C5 in an active manner internationally. At the same time, China should work hard to pull U.S. back.