Abstract: There occurs an Early Jurassic intrusive complex belt in Xuzhou-northern Anhui province which is distributed in NE direction parallel to Tan-Lu Fault.It is mainly composed of diorite and monzodiorite.The 40At／39Ar plateau ages of hornblendes from diorite and monzodiorite are in the range of 189～191Ma.The eclogite,garnet-pyroxenite and clinopyroxenite xenoliths are found in this intrusive complex.Abundant exsolved quartz rods and exsolution lamellae of garnet are identified within or between clinopyroxenes of eclogite, garnet-clinopyroxenite and clinopyroxenite xenoliths under microscope.The core of the omphacite,in which quartz rods occur,is relatively poor in SiO2,Al2O3,CaO,but rich in FeO and MgO than its rim.There is also a systematic compositional change within the clinopyroxenes containing exsolved garnets：the core is obviously rich in A12O3,Na20 and TiO2,and the rim in contact with exsolved garnet is rich in Mgo,SiO2 and CaO.The garnets exsolved within clinopyroxene are similar to those exsolved between clinopyroxenes in mineral chemistry,which indicates their exsolution origin.A spectacular microstructure of oriented quartz rods within clinopyroxene implies preexistence of silica-oversaturated omphacite stabile at ultrahigh pressure(≥ 25kbar)conditions.The existence of exsolved garnet within single clinopyroxene crystal indicates that decrease of temperature and pressure would be a major cause of exsolution. Therefore, we conclude that most exsolution microstructures in the xenoliths may have been resulted from the decomposition of very high pressure precursor phases(clinopyroxene)due to decrease of pressure and temperature(especially pressure).The mineral assemblage and petrography of the xenoliths show that the xenoliths were subjected to eclogite-facies metamorphism and amphibolite-facies retrogresive metamorphism ,which is consistent with mineral exsolution due to decrease of presure.The discovery of high-pressure xenoliths and mineral exsolution will be helpful for us to understand the subduction and exhumation history of Dabie-Sulu UHP metamorphic belt.