2000年美国以68票的绝对优势在参议院通过了对华的永久性正常贸易关系（PNTR）议案，从而结束了美国国会长达20年的对中国贸易地位年度审议引起的激烈争论，这一议案的通过极大促进了中美之间的正常贸易伙伴关系的发展。2001年中国加入世贸组织，自此进入了对外贸易迸发的大时代。2008年以美国为起点的次贷危机引爆全球，各国相继爆发金融危机，从金融行业到实体经济，使得各国宏观经济收到显著影响。各国政府为应对和控制金融危机的蔓延，积极调整经济政策，试图通过经济政策来减缓经济的衰退和加强金融风险监管，但是从后危机时代来看，各国频繁调整的经济政策使得经济主体无法准确的预知政府对于现有的经济政策的态度，导致各国经济政策不确定性显著提高。大量的文献表明本国经济政策不确定性对本国的系统性金融风险有显著的正向作用，而美国作为中国最大的贸易合作伙伴，美国的经济政策不确定性也在2008年之后显著上升，因此研究美国经济政策不确定性对中国的系统性金融风险的影响基期传导机制，对中国如何防范和化解外部经济政策不确定性对本国金融安全的问题有重要的现实意义。

首先，本文采用了2006年1月到2022年3月的月度数据，计算了期限利差、银行业风险利差、股票市场波动性以及EMPI（外汇压力指标）等四个指标构建中国的金融压力(Financial Stress Index, FSI)指数用来反映中国的金融安全。其次，利用Baker等人计算的基于新闻报纸测度的美国经济政策不确定性指标(US-Economic Policy Uncertainty,USEPU)。并且引入了汇率作为中介变量进行中介机制检验。分析结果如下：

（1）美国经济政策不确定性对中国的系统性金融风险具有显著的正向原因。即美国经济政策不确定性的上升会促使中国的系统性金融风险不断累积，金融压力指数不断攀升。（2）以人民币兑美元的实际有效汇率作为中间变量进行中介机制检验发现，美国经济政策不确定性会对人民币汇率有显著的负向作用，人民币汇率对中国系统性金融风险也有显著的负向影响，即美国经济政策不确定性可以通过人民币实际汇率对中国系统性金融风险产生正向影响。（3）引入中美双边贸易增长率作为中介变量进行中介机制检验发现，美国经济政策不确定性对中美双边贸易增长率呈现出显著的负向作用，中美双边贸易增长率对中国系统性金瓯荣那个风险也呈现出明显的负向作用，中介作用显著。从而得出结论，美国经济政策不确定性可以通过中美双边贸易增长率这一中介机制对中国系统性金融风险产生正向的影响。

本文的创新之处在于，一、引入了Baker等人测度的美国经济政策不确定性作为本文的主要解释变量。二、考虑到中国2005年的汇率改革，选取了2006年到2022年的数据作为本文的观测数值。三、引用汇率和中美双边贸易变化率作为中介传导机制，探究美国经济政策不确定性对中国金金融安全的影响。

In 2000, the United States passed the Senate's permanent normal trading relationship (PNTR) proposal to China with the absolute advantage of 68 votes in 2000, thereby ending the fierce debate caused by the 20 years of the US Congress for the annual review of China's trade status. This proposal It has greatly promoted the development of normal trade partnerships between China and the United States. In 2001, China joined the WTO, and has since entered a major era of foreign trade. In 2008, the subprime mortgage crisis from the United States has detonated the world. The financial crisis broke out in various countries. From the financial industry to the real economy, the macroeconomics of various countries received a significant impact. In order to cope with the spread of the financial crisis, governments of various countries actively adjust their economic policies, trying to slow down the economic recession and strengthen financial risk supervision through economic policies. The predicted government's attitude towards existing economic policies has led to a significant improvement of economic policies from various countries. A large number of literature shows that the uncertainty of the country's economic policy has a significant positive effect on its systematic financial risks. As China's largest trading partner, the United States' economic policy uncertainty has also risen significantly after 2008, so Studying the influence of U.S. economic policy uncertainty on China's systematic financial risks, the foundation period conduction mechanism, which has important practical significance for how China to prevent and resolve the uncertainty of external economic policies on the issue of domestic financial security.

First of all, this article uses monthly data from January 2006 to March 2022. It calculates four indicators such as term spreads, banking risk spreads, stock market volatility, and EMPI (foreign exchange pressure indicators) to build China's financial pressure Index is used to reflect China's financial security. Secondly, use Baker et al. Calculated the US economic policy uncertainty indicators measured by news newspapers. And the exchange rate was introduced as an intermediary variable for intermediary mechanism testing. The analysis results are as follows:

(1) U.S. economic policy uncertainty has significant positive reasons for China's systemic financial risks. That is, the rise in U.S. economic policy uncertainty will promote China's systemic financial risks to continue to accumulate, and the financial pressure index will continue to rise. (2) The actual valid exchange rate of the RMB against the US dollar is inspected as an intermediate variable in the intermediary mechanism. It is found that U.S. economic policy uncertainty will have a significant negative effect on the RMB exchange rate. The influence is that the uncertainty of the US economic policy can have a positive impact on China's systemic financial risks through the actual exchange rate of the RMB. (3) The introduction of Sino-US bilateral trade growth rate as an intermediary variable for intermediary mechanism testing shows that the uncertainty of US economic policy has a significant negative effect on the growth rate of Sino-US bilateral trade, and the growth rate of Sino-US bilateral trade also shows an obvious negative effect on the risk of China's systemic Jin Ou Rong, and the intermediary role is significant. Therefore, it is concluded that US economic policy uncertainty can have a positive impact on China's systemic financial risk through the intermediary mechanism of bilateral trade growth rate between China and the United States.

The innovation of this article is that the U.S. economic policy uncertainty measured by Baker and others as the main interpretation variables in this article. 2. Considering China's exchange rate reform in 2005, the data from 2006 to 2022 was selected as the observation value of this article. Third, the exchange rate and The rate of change in bilateral trade between China and the United States are used as intermediary conduction mechanism to explore the impact of U.S. economic policy uncertainty on China's financial security.