Mercury alteration, a kind of black alteration related to Hg element, is a special one among several types of alteration of Chinese ancient jades. Mercury alteration often appears on ancient jade artifacts unearthed from high-grade tombs of the pre-Qin period (before 221 B.C.). Therefore, study on ancient jades with mercury alteration has attracted a lot of attention of Chinese archaeologists. Materials analytic techniques were used to study the ancient jade fragments in this paper. These jade samples, dating to the middle and late period of the Spring and Autumn Period (~500 B.C.), were unearthed from the Lizhou’ao Tomb in Jiangxi Province of China. The structure analyses showed the internal micro-structure of the ancient jade fragments and the micro-distribution of mercury alteration. The jade fragments showed typical characteristics of round holes and structural hierarchy, which imply that the jades were heated before buried. The black alteration on these jade samples was detected rich in Hg element. The result of this study will be widely used in ancient jade study and jade culture study in Chinese archeology.