The Permian volcanic rocks are widely distributed in the central part of the Xingmeng orogenic belt, and consist of basalt, basaltic andesite, bryanite, rhyolite and pyroclastic rocks and therefore are important for addressing secular tectonic evolution of the Xingmeng orogenic belt during the Late Paleozoic. In this study, we carried out geochemical and geochronological investigations for the newly identified high- magnesium andesite in the eastern part of Lindong area of eastern Inner Mongolia to explore their petrogenesis and geological significance. The rocks are grayish black and gray, porphyritic in texture. The porphyric minerals include plagioclase (15%~20%), othopyroxene (5%~10%), clinopyroxene (5%) and hornblende (5%), whereas magnetite and ilmenite are abundant in the matrix, indicating water- rich and oxidized character. They have zircon U- Pb ages of 253±1 Ma to 255±1 Ma. They have moderate SiO2 (52. 3%~56. 5%), high MgO (7. 2%~12. 7%), Cr (264×10 -6 ~382×10 -6 ), Ni (168×10 -6 ~407×10 -6 ), Ba (318×10 -6 ~1130×10 -6 ) and Sr (288×10 -6 ~906×10 -6 ), Mg # (60. 0~77. 2), similar to those of Sanukitic- type high- magnesium andesites. They have low whole rock initial ( 87 Sr/ 86 Sr)i (0. 70348~0. 70454), high ε Nd ( t ) (+3. 79~+7. 57) and high zircon ε Hf ( t ) (+7. 8~+14. 3). Meanwhile, they have high La/Sm ratio (1. 68~8. 67). These lines of geochemical evidence indicate that the high- magnesium andesites originated from a metasomatic mantle that was modified by slab- derived materials. We propose that the formation of these high Mg andesites is related to the partial melting of the lithospheric mantle metasomatized by water rich fluids from subducted sediments. In addition, the basalt associated with high magnesium andesite has typical island arc volcanic characteristics. Therefore, it is believed that the high- magnesium andesite in Lindong and its associated basalts were formed in the island arc environment and were related to the northward subduction of the ancient Asian Ocean. The age of high- magnesium andesite is the Late Permian, which provided chronological constraints for the final closure of the ancient Asian Ocean.