The chemical composition and mineral inclusions preserved in garnet can be used to constrain the P-T conditions, metamorphic evolution, and fluid action. The chemical composition of garnet is related to many factors, such as whole-rock composition, P-T conditions, garnet-forming metamorphic reactions and the assemblage of coexisting minerals. Thus the major elements, trace elements, oxygen isotopes, mineral inclusions and their relations in garnet should all be taken into account when it is used to constrain the metamorphic P-T evolution in UHP metamorphic rocks.