Metallurgical studies of the bronze artifacts excavated from Miruksa Temple were performed by chemical analysis and metallographic observation. Alloy systems of the bronze artifacts were classified into two groups of Cu-Sn and Cu-Sn-Pb, according to the items. The contents of impurities such as Sb, As, Ni and Fe in bronze artifacts are within the limiting range of the mod ern standard bronze castings. Chemical compositions of the kitchen utensils such as bronze vessels and dishes in the Unified Silla dynasty, are in the follow ing range, Cu : 74.8-79.4% and Sn : 18.6-21.1%. Chemical composition of the Buddha-image in Koryo dynasty are 820Cu-7.0Sn-10.3Pb, showing increased Pb content and decreased Sn content. The results of chemical analysis suggest that the chemical compositions were good controlled. Any casting defects such as voids and shrinkage holes are not found microscopically, indicating high casting skill. Zinc atoms are not contained in the all bronze artifacts of Miruksa Temple site. This is the common facts founded in the east asian bronze artifacts of Korea, China and Japan. It is comparable with the European bronze of Cu-Sn-Pb-Zn system, after the Middle Age.