It is necessary to keep the exchange rate stable. From the macroeconomic point of view, to improve the actual economic chaos caused by exchange rate changes, it is necessary to maintain the stability of the exchange rate. If the price of imported products rises due to the rapid depreciation of the exchange rate, it is easy to shift to domestic wages and raw material costs; However, the decline in the prices of imported products caused by the appreciation of the exchange rate cannot reduce the prices of wages and raw materials. Therefore, if both wages and prices show the downward rigidity or "stickiness" of the traditional Keynesian school, then when the overall price inflation is at a low level, official intervention aimed at slowing down exchange rate fluctuations will play a role and will also affect the psychological expectations of market participants. Donne Bush's "exchange rate overshoot model" also shows that in the process of adjusting the short-term equilibrium exchange rate to the long-term equilibrium exchange rate, exchange rate fluctuations will exceed the long-term equilibrium level, leading to excessive exchange rate fluctuations, which will impact and destroy the financial market and the real economy, thus putting forward requirements and providing a basis for the central bank to intervene in the foreign exchange market. In addition, the theory of "non-sterilisation intervention" also provides a theoretical basis for the central bank to intervene in the foreign exchange market without sterilisation.