This paper examines the policy framework of Reaganomics and its impact on the global economy to explore the origins, internal logic, and potential global impact of the Trump 2.0 policy system. The study finds that the governance philosophy and policy design of Trump 2.0 inherited the core pillars of Reaganomics and further intensified the policy measures. In the economic policy realm, Trump 2.0 continues Reagan-era supply-side reforms such as tax cuts, deregulation, and reductions in government spending, while introducing more radical tariff policies and industrial support strategies in an attempt to reshape incentives to boost U.S. economic growth and manufacturing revival. Although these policy continuities and innovations may stimulate short-term U.S. economic performance, they pose long-term risks of exacerbating U.S. fiscal deficits, debt crises, and social inequality. From an international perspective, Trump 2.0’s unilateralism and protectionism are more likely than Reagan’s policies to escalate global trade conflicts, accelerate the fragmentation and balkanization of global trade patterns, increase the economic and financial vulnerability of developing countries, and potentially shift the international order from a rules-based cooperative system to a transactional mode, posing a serious challenge to the stability and sustainable development of the global economy. This paper provides a historical and theoretical perspective for understanding the global impact of Trump 2.0’s policies and offers insights for addressing the uncertainties of the future international economic landscape.