The Taohe mafic rock is located in Langao County of Daba Mountain. The types of Taohe mafic rock are consistent with those of regional mafic rocks, mainly consisting of diabase, gabbro, gabbro diabase and kaersutite-rich diorite, with the adjacent mafic rocks showing a gradual transition state, indicating the same period of magmatism. The amphibole inside the diorite is kaersutite, characterized by long stripe and needle megacrystal, particle size of 1~3 cm, obvious euhedral crystal, and significant high aluminum (Al=1.93~2.06) and high titanium (TiO₂=4.54%~5.50%). The temperature is 1062~1129℃, the formation depth is 19.11~22.64 km, and the oxygen fugacity ranges from NNO=-0.36 to NNO=-0.01. The magma was derived from deeper source and intruded rapidly. The presence of kaersutite shows an apparent mantle metasomatism before the partial melting, and mantle metasomatism and formation of mafic rock had a necessarily close connection with subduction. Obvious deep source characteristics and subduction-related and crustal contamination characteristics indicate that the Taohe mafic rocks were formed in an extensional environment related to subduction.