Based on Chinese historical sources, the article learns about the total Qing troops killed in Vietnam during the battle in the early spring of "Ky Dau" year (1789). Regarding the number of combatant forces, the Qing Dynasty mobilized 2 armies to attack Vietnam: The Luong Quang army of 21,500 Qing soldiers, including the great army of about 12,500 stationed in Thang Long, and the Van-Quy army of 8,000 soldiers who quickly retreated right after the heavy defeat of the great army in Thang Long. In addition to regular army also have auxiliary forces such as local forces, militia, ect with large numbers of tens thousands of people. Regarding the number of troops killed in battle, based on the records in the Annals of the Qing Dynasty relating officers and soldiers killed (during the aggression in Annam), subsidized and worshipped in Chieu Trung temple, the number of Qing troops killed in Vietnam were 11,782, including 188 military offices of various ranks. The documents only deal with the losses of the regular army, not with auxiliary forces such as local forces, militia, etc.