Of course, American bonds are bought in foreign exchange, that is, dollars. First of all, we should know that China's huge foreign reserves depend on exports. With the long-term efforts of enterprises in the Yangtze River Delta and the Pearl River Delta, the vast number of migrant workers and importers and exporters, China has maintained an increasingly prosperous export scale for decades, and also maintained a large number of migrant workers' employment. China's long-term export growth is strong, and all the goods exported abroad are settled in foreign currency (mainly in US dollars), which leads manufacturers to exchange US dollars for goods. When they return to China, they will definitely buy raw materials again to organize production, pay workers' wages or expand reproduction, and the US dollar is not circulating in China, so manufacturers find banks and exchange their US dollars for RMB.