The United States has always been a significant country in the world. And its major economic problems caused by various reasons (e.g., health events or collapsing of the financial system) are widely noticed around the world. They can also affect other regions and countries to a greater extent. The paper examines several major financial events in U.S. history based on a literature survey and case study approach in chronological order, namely, the Great Depression, the U.S. subprime mortgage crisis, and the economic recession to recovery since the New Crown epidemic, the paper as well as shows the macroeconomic policy regulation and policy effects adopted by different governments behind them, and finally gives relevant economic policy recommendations. This paper points out the uncertainty of economic policies and the impact of policy implementation on other countries especially countries which close contact with America. And the policies adopted by the U.S. government in getting out of several economic events have solved specific problems. They are worthy of being used by governments today to prevent related situations, reduce the impact of financial losses on society, make the government vigilant, and take strict precautions.