A trade war initiated by unilateralism will seriously affect the confidence of all parties in the commitment made by the United States, and weaken the credibility of the US in the global economic governance system. The imposition of tariffs by the US not only undermines the ability of enterprises to allocate resources across borders in accordance with market economic principles, but also has a greater impact on the balance of supply and demand. Producers, consumers and employees from the US will all be deeply affected. Besides, given that the adjustment of monetary and taxation policies has led to the increase of global capital flow to the US, market inflation pressure will probably rise, asset bubbles may increase, and the gap between the rich and the poor in US society may be wider.