Abstract: Based on the implementation of the unconventional monetary policies by the Federal Reserve and the European Central Bank from 2008 to 2021, this study divides the implementation stages and policy types uniformly, compares the policy tools and transmission mechanisms of the United States and Europe, and uses the TVP-VAR model to compare the policy transmission effects of different channels, so as to explore the time, performance and reasons for the differentiation of unconventional monetary policies in the United States and Europe. The findings show that unconventional monetary policies in the United States and Europe have differentiated in the early stages of crises and the crisis responding stages, exhibiting multi-dimensional differentiation in terms of operation stage, policy tools, policy objectives, and policy effects. The differences in such aspects as economic fundamentals, sources of crisis outbreaks, crisis response methods, and policy implementation effects between the United States and Eurozone countries have led to the multi-dimensional differentiation of unconventional monetary policies between the Federal Reserve and the European Central Bank. Based on the policy characteristics and the basic national conditions, when implementing unconventional monetary policies, China should strengthen risk control and attach importance to international risks, implement strategies timely and precisely, make good use of tool combinations, strengthen policy communication, make clear commitments, grasp the overall economic situation, and coordinate the policies.

Key words: unconventional monetary policy, international comparison, policy differentiation, TVP-VAR model