Abstract: The ophiolite and late Paleozoic low-grade metamorphic rock series have been found in Guoganjianian Mountain, in Longmucuo-Shuanghu-Langcangjiang suture zone. The eclogite is newly found in this area. It occurs as lenses in garnet-muscovite schist, and mineral grains are very fine, ranging from 0.05 mm to 0.1mm. The eclogite consists of garnet, omphacite, phengite and rutile. Data in this paper indicate that the eclogite was formed under low-temperature condition of 470～520℃ and high-pressure of 2.21～2.51GPa. The study on forming process of the eclogite has great significance for the tectonic evolution of Longmucuo-Shuanghu-Langcangjiang suture zone.