From 2014 to 2019, the Vietnam National Museum of History, in collaboration with Japanese researchers, carried out several surveys and excavations at the ancient citadel of Luy Lau, which was considered as one of the earliest and largest metropolises in Northern Vietnam during the first ten centuries AD. It is noteworthy that during the excavations in 2014 and 2015, archaeologists discovered hundreds of fragments of ceramic moulds for bronze drum casting that have been in situ in the culture layer. This discovery provides compelling evidence that the Dong Son drums were made in the central region of North Vietnam and opens the door for us to thoroughly understand the ancient Viet people's drum casting process. The significance of this discovery becomes even clearer in the context of the current situation of the Dong Son drum casting technology. Therefore, in this article, we will review the research situation of the Dong Son drum casting technique, which revolves around three main subjects: (i) methods of drum casting; (ii) alloy composition; and (iii) experimental research. Based on this, we will draw some remarks on the significance of the discovery of bronze drum casting moulds within the archaeological stratigraphy of the ancient Luy Lau citadel - one of the greatest archaeological discoveries in recent years of Vietnam.