The depreciation of the renminbi means the appreciation of the dollar. At this time, the purchasing power of the dollar increased. The appreciation of the dollar means that the United States has been running a trade deficit, while China is achieving a trade surplus. Therefore, the root of the Sino-US trade war in recent years is that the United States believes that China has always had a trade surplus and requires China to change this trade surplus and import a large number of agricultural products from China. Therefore, this is the fundamental reason why the United States is unwilling to devalue the RMB. The appreciation of RMB is the increase of its purchasing power relative to other currencies. The reason of RMB appreciation comes from the internal motivation and external pressure of China's economic system. Internal factors include balance of payments, foreign exchange reserves, price level and inflation, economic growth and interest rates. Therefore, the United States is afraid of RMB depreciation.

1. Trade surplus means that the total export trade of a country is greater than the total import trade in a certain year, which is also called "surplus", indicating that foreign trade in that year is in a favorable position. The scale of trade surplus largely reflects a country's foreign trade activities in a certain year. Under normal circumstances, a country should not have a huge trade surplus for a long time, because it is easy to cause friction with relevant trading partners. For example, one of the main reasons for the market fluctuation in the bilateral relations between the United States and Japan is Japan's long-term huge surplus. At the same time, a large amount of foreign exchange surplus usually increases the domestic money in a country's market, which is easy to cause inflationary pressure and is not conducive to the sustained and healthy development of the national economy.

2. In foreign trade, if a country's exports exceed its imports in a certain period of time (usually one year), it is called surplus, that is, trade surplus, which indicates that a country obtains net income from foreign exchange and its foreign trade increases. Foreign exchange reserves, bulk commodities have strong international competitiveness and are in a favorable position in the international market; If the import volume exceeds the export volume, it is called surplus, that is, trade deficit or trade deficit. It shows that a country's foreign exchange reserves are decreasing, and its commodities are in a weak position in international competition and in the international market.

3. Exchange rate refers to the exchange rate between two currencies. It can also be regarded as the value of one country's currency to another's currency. Specifically, it refers to the ratio or price ratio between one country's currency and another's currency, or the price between another country's currency and another country's currency. The fluctuation of exchange rate has a direct regulating effect on a country's import and export trade. In some cases, by devaluing a country's currency, that is, by raising the exchange rate, exports can be promoted and imports can be restricted. On the contrary, the appreciation of local currency against foreign currency, that is, the decline of exchange rate, will restrict exports and increase imports.