There are many sources of money, the fundamental reason is that China implements foreign exchange control and RMB exchange rate control. In other words, when paper money goes in and out of China, it has to go through an institution to exchange the corresponding currency. This institution is called the Central Bank.

For example:

American company bought a shirt of $65,438 +0w from China company. This money was not directly remitted by American company to China company, but remitted by American company to the central bank of $65,438 +0w, and the central bank gave the corresponding 6W (for example) RMB to China company, so the central bank had $65,438+0w;

Let me give you another example, which is actually very similar to the first one: an American company wants to invest and set up a factory in China, and has prepared $65,438 +0W. Like the previous example, it will go to the central bank to change into RMB, and then use RMB at home. In this way, the Bank of China added another $65,438 +0W. Of course, if China companies buy things abroad, it is an opposite exchange process.

As we all know, China is a factory in the world, producing many things and selling them all over the world. At the same time, with the development of China's economy and huge market scale, many foreign companies invest in China. So now China's trade is in surplus every year (more money comes in, less goes out), so that the Bank of China has accumulated a large sum of dollars year by year.