A set of meta-argillaceous rocks mainly composed of biotite plagioclase gneiss has been newly discovered in Caojian, Yunlong County, western Yunnan Province, which is produced in the form of structural lenses, with small outcrops and developed medium-high metamorphic minerals, which is obviously different from the surrounding rock characteristics. Petrographic study shows that gneiss has obvious mineralogical records of subduction-exhumation, and there is also a paragenetic mineral assemblage of kyanite+aluminum amphibole, and the corresponding metamorphic pressure should reach 1.0 GPa or above. The metamorphic temperature and pressure range of rocks calculated by GBP average temperature and pressure meter method is 566~623°C and 0.36~0.53 GPa；. In addition, there is a small amount of siliceous muscovite minerals in gneiss. According to the P-T visual profile of phase equilibrium simulation and the characteristics of its maximum silicon atomic weight of 3.23, it is inferred that it belongs to blueschist. According to the comprehensive study, the biotite plagioclase gneiss belongs to high-pressure metamorphic rocks (the minimum metamorphic pressure in peak period is about 1.60 GPa), which provides new information for finding high-pressure metamorphic rocks in the northern part of Changning-Menglian junction zone, and shows that Changning-Menglian junction zone is a continuous high-pressure and ultrahigh-pressure metamorphic zone.