China's high copper demands and poor mineral endowments have led it to rely heavily on the international copper trade. However, the importance of the metal trade has not been adequately appreciated. This study explores the role of metal trade in copper security through a high-resolution material flow analysis of China's copper cycle from 1950 to 2015 that covers over 300 types of copper-containing products. We found that the annual inflow of copper has increased from 4.3 KT/yr to 14 MMT/yr from 1950 to 2015, which drove the increase of copper stocks accumulated in buildings, infrastructures, and products from 7 kg/cap to 56 kg/cap. The total copper in-use stocks in China were approximately 80 MMT in 2015. However, about 70% of all copper used in China in this period was imported from other nations. Thus, this study indicates that more attention should be paid to the importance of the copper waste trade in China.