中文摘要：

国际金融危机以来,美国深陷高赤字、高失业、低增长的＂两高一低＂的经济困局。对美国财政政策的研究表明,提振经济的扩张性财政政策受到法定债务上限的制约,美国面临着财政政策的选择困境。对美国货币政策的研究表明,零利率政策由于信号效应的损失不但未能有效产生预期政策效果,而且丧失了后续操作空间;两轮量化宽松货币政策因流动性陷阱而不具备长效性;＂扭曲操作＂本质上不可能改变美国的经济走势,因此美国也面临着货币政策的选择困境。深陷经济困局、面临经济政策选择困境的美国,未来在维持扩张性货币政策的同时,可能将进入财政政策的紧缩期,其最坏的结果是将美国经济拖入长期＂滞涨＂。

英文摘要：

Since the outbreak of international financial crisis, America is trapped in ＂two high and one low＂ economic dilemma, that is, high deficit, high unemployment rate, and low growth rate. A study on American fiscal policy shows that the expansionary fiscal policy boosting the econ- omy is subjected to Statutory Limits on Federdt Debt, therefore, America is confronted with the choice dilemma of fiscal policy. A research of American monetary policy shows that, because of the failure in signal effect, the policy of zero interest rate not only fails to cause the expected effect, but also loses the following action space; because of a liquidity trap, two rounds of quantitative easing monetary policy do not have long-term function; ＂ Operation Twist＂ is essentially impossible to change the American economic trend, actually it bring America into a monetary policy choice dilem- ma. America is faced with the dilemma of economic policy claoices, and in the future it may maintain expansionary monetary policy, and enter into a period of austerity of fiscal policy, its worst result is that American economy will enter into a long--term ＂stagflation＂.