The question of why the dollar is valuable is why the dollar is a strong currency, even the most powerful currency in the world, which can be said to be the world currency. I think someone replied that 1 USD was converted into 6-8 yuan RMB, so USD was valuable. There is nothing wrong with this sentence alone, but there is something wrong with the logic when it is combined. The main functions of money are trading tools, value measurement and collection. From this point of view, the direct reasons for the strength of the US dollar are as follows: First, the value of the US dollar is stable; Second, international trade is mostly denominated in dollars; Third, the US dollar is the bulk of the foreign exchange reserves of major countries in the world.