Among coin currencies, there were the coins bearing the regnal year of Qianlong and Quang Trung on the obverse and the inscription of "Annam" on the reverse, which has drawn attention of ancient coin collectors and researchers. There have been many strong debates around these coins due to political tendencies or feelings. Based on the viewpoint of considering "Annam" the official name of our country in the relation of "celestial empire-vassal" with China, the author reckons that the appearance these coins was an expression of that relationship. The coin of Qianlong-Annam came to be used in Vietnam in order to confirm the possession of the Qing troops when invading Vietnam, as what the Qing Dynasty did for other vassals. Meanwhile, the coin of Quang Trung-Annam appeared after Quang Trung was recognized as King of Annam in 1789, which meant to confirm the power for the need of the legitimacy of King Quang Trung in internal and external affaires. If these coins are placed in the right context of the history of that time, people will see their appearance is not a great event in the history of ancient Asian coins.