Abstract: Kosmochlor-jade and related amphibole-jade (rock) in Longken, Myanmar are studied. Their types, texture, mineral chemistry, X-ray powder diffraction spectrum，chemical composition and REE of whole rocks, etc， are elucidated. The protoliths of kosmochlor-jade and related amphibole-jade (rock) in Longken, Myanmar are considered as peridotites, chromite-bearing peridotites, or chromite bodies, respectively. At high or ultrahigh pressure, those protoliths reacted with SiO₂, Na₂O and Al₂O₃ melt through a series of metamorphism. Chromite was replaced mainly by kosmochlor, astridite or chromium-bearing jadeite, while peridot was replaced by chromite. As a result, there might be a contin-uous variation from amphibole-jade (rock) to kosmochlor-jade.