For a long time, the harm of deflation is often ignored and considered to be far less than the threat of inflation to the economy. However, the historical lessons of deflation and the grim reality of global deflation force people to realize that deflation, like inflation, will cause serious harm to economic development. Moreover, it is difficult for policymakers to prevent deflation. Or reverse the trend of deflation. 1. Accelerate the economic recession. The economic recession caused by deflation is manifested in three aspects: first, the sustained and general decline in prices makes the prices of enterprise products fall, and the profits of enterprises decrease or even lose money, which will seriously hit the enthusiasm of producers and make them reduce or even stop production. As a result, the economic growth of society is suppressed. Second, the sustained and general decline in prices has led to an increase in real interest rates. This will benefit creditors and harm the interests of debtors. Most debtors in society are producers and investors, and the increase of debt burden will undoubtedly affect their production and investment activities, thus having a negative impact on economic growth. Third, the decrease of enterprise profits and production enthusiasm caused by falling prices will increase the unemployment rate and the actual employment rate below full employment rate. Real economic growth is lower than natural growth. 2. Social wealth has shrunk. 3. The negative influence of distribution has appeared. This may lead to banking crisis. Contrary to inflation, deflation is beneficial to creditors and harmful to debtors. Deflation makes money more and more expensive, which actually increases the borrower's debt burden, making it impossible for the borrower to repay the loan, thus leading to a large number of non-performing assets in banks, even bankruptcy and financial system collapse. Therefore, many economists pointed out: "Currency appreciation is