中文：

负利率是指银行向储户收取存款利息的情形，也就是说，存款不仅没有利息，还要支付一定的费用。负利率主要出现在经济不景气时期，央行通过降低存款利率来刺激消费和投资，以促进经济增长。

负利率的出现主要是因为经济不景气导致货币需求量下降，而货币供应量却相对充足。在这种情况下，央行通过降低存款利率来减少储蓄，增加消费和投资，从而刺激经济增长。负利率还具有调节货币供应量的作用，当货币供应量过剩时，通过降低存款利率可以促进货币流通，从而调节货币供应量。

然而，负利率也存在一些问题。首先，它不利于储蓄和投资，因为储蓄和投资的收益会减少。其次，它可能会导致通货膨胀加剧，因为降低存款利率会刺激消费和投资，从而增加货币需求量，导致物价上涨。最后，它可能会对金融稳定造成影响，因为负利率可能会导致银行利润减少，从而影响金融体系的稳定。

总的来说，负利率是一种货币政策工具，它主要用于经济不景气时期。然而，它也存在一些问题，因此央行在使用负利率时需要谨慎。

英文：

Negative interest rate refers to the situation where banks charge depositors interest, which means that deposits not only have no interest, but also have to pay a certain fee. Negative interest rates mainly appear during periods of economic downturn, when the central bank reduces deposit rates to stimulate consumption and investment and promote economic growth.

The emergence of negative interest rates is mainly due to the decline in monetary demand during economic downturns, while the supply of money is relatively sufficient. In this case, the central bank reduces deposit rates to reduce savings, increase consumption and investment, and thereby stimulate economic growth. Negative interest rates also have the function of regulating monetary supply. When there is an excess supply of money, reducing deposit rates can promote the circulation of money and thereby regulate monetary supply.

However, there are also some problems with negative interest rates. Firstly, it is not beneficial to savings and investment because the returns on savings and investment will decrease. Secondly, it may lead to an increase in inflation because reducing deposit rates will stimulate consumption and investment, thus increasing monetary demand and leading to price increases. Finally, it may have an impact on financial stability because negative interest rates may lead to reduced profits for banks, thus affecting the stability of the financial system.

Overall, negative interest rates are a monetary policy tool mainly used during periods of economic downturn. However, there are also some problems with it, so central banks need to use it cautiously.