Objectives: The ultramafic vitric dunite, that is meimechite, also known as a igneous rock, rarely appear all over the world, has been found in Permian diorite (δP) for the first time in southern Beishan Mountain, China. The vitric dunite sample shows as dense mass and celandine green with weakly magnetism, and has clear granular porphyry minerals and black cement with small hairlike bands on the surface. While, the alteration vitric dunite samples show as dense mass and deep darker black with weakly magnetism and small vein material. However, the petrology and geochemistry of this important rock, as well as the formation of the environment, are not well understood. Based on a lot of results of lab identification, testing, analysis, we focus on the every characteristics and formation mechanism of this rock. Methods: Laboratory, Xi’an Institute of Geology and Mineral Resources. ① Microscopical identification and Mineral porphyry contrast. ② Xray diffraction analysis in D/max2500 instrument. ③ The detection of electron probe in JEOL JXA8230 instrument and equipment. ④ Petrochemical analysis: FeO analysis use volumetric method，LOI and H2O+ analysis use gravimetric method，the other main elements analysis use XrfXrd Spectrometry, Trace elements and REE elements analysis use Plasma Mass Spectrometer ICPMS method. ⑤ Trace elements and REE elements standardization, tectonic environment discrimination.Results: ① Under the microscopical identification, the main minerals of the vitric dunite, they contain only large phenocrysts of olivine, are porphyritic texture. Yet not, the alteration rock, the main minerals, they contain abundant large phenocrysts of olivine and serpentine, are blastoporphyritic texture.The phenocrysts are serpentinized olivine illusion. Groundmass of the each sort is glass structure. ② Results of Xray diffraction analysis, olivine is forsterite \[(Mg1.8Fe0.2) (SiO4)\], serpentine is lizardite 〖JB（{〗(Mg,Al)3\[(Si,Fe)2O5\](OH)4〖JB)}〗. ③ By the detection of electron probe, the meimechite samples comprise of these minerals. Serpentinized veins show as deep colour across the main phenocrysts and the matrix, Larger bright fine stripe magnetites are found in the olivine, while the finegrained groundmass contains chlorite，epidote，zoisite，hornblende，ilmenite，limonite，pentlandite，plagioclase，spinel，phlogopite, and serpentinized glass, besides the main minerals olivine and serpentine. ④ Chemical compositions data on the rock from this area are reported . They are low in SiO2 (36.40% ~37.29%) and Al2O3 (2.61%~4.70%) and TiO2(0.058%~0.22%)and Na2O+K2O (0.03%~0.14%); Relatively, high in MgO (33.30%~35.36%) and Fe2O3+FeO (10.51%~12.89%). It is a especial ultramafic extrusive rock. Mg#= 83.5~86.5，δSr =1.14~4.61，Sr/Y=5.70~42.74。∑REE =2.18~9.71，δEu=0.68~2.43，La/Yb=0.90~10.00。Trace elements and REE elements have the lithologic characteristics of the primitive mantle. Conclusions: 〖WTBZ〗① The original magma may undergo the process of crystallization and differentiation, and also, which is supposed to be formed in the rift valley tectonic environment. ②We propose that the rocks are compositionally similar to type Siberian meimechites and closely resemble the “Meimechite”– low in TiO2 eruptives of Meimechite from Maimecha—Kotui Province and Kamchatka peninsula. The finding of the rocks in this region, has extremely important significance for the study of the formation and evolution of magma, and the prospecting and exploration of copper and nickel ore deposit.