In recent years,several Carlin-type gold deposits have been found in Hunan-Guizhou area. Some of these deposits are stratiform ones on tops of the paleokarst denudation planes, and others are tabular ones extending along faults. Chemical phase analysis was carried out to study the mode of occurrence of gold in the gold deposits,and the results show that,in primary ore,the content of free gold is very low, with above 95% of gold encapsulated in pyrite and sericite.In ore deposits on tops of the paleokarst denudation planes, sericite is the most important carrier of gold, whereas in the ore deposits within the faults, pyrite is the most important carrier of gold. The close spatial association of gold with pyrite and sericite suggests that the deposition of gold was synchronous with the growth of pyrite and tbe recrystallization of sericite. The gold microparticles encapsulated in minerals can not be leached by cyanidation. In the supergene process, pyrite and sericite in primary ore are oxidized and decomposed. The gold microparticles encapsulated in those minerals are released and then accrete into larger particles. In oxidized ore, 80% of gold is free gold, and thus the economic value of the ore improves greatly.