Abstract: Baimajian granitoids in Dabie Ultra High Pressure(U )belt are mainly composed of monzogranite.Pertrographical and geochemical characteristics indicate that they were emplaced in the post-collision regime(1ate Yanshan period).The granitoids belong to the metaluminous-peraluminous transitional type on Shand diagram (ACNK-ANK diagram (ACNK = 0.97～1.01)),and belong to high-K calc-alkaline series on K2O vs silica diagram.REE pattern diagram shows that they are rich in LREE,with strong negative Eu anomaly(δEu=0.37～0.65,average 0.53).The Nb-Y,Rb-Y+Nb,Rb-Hf-Ta diagrams indicate that the source materials of the Baimajian granitoids were possibly derived from the old island arc,though they cannot exactly reflect the tectonic background of the intrusion activity.Mantle upswelling associaed with extension process during the Yanshanian movement not only created the geotectonic conditions for granitoids formation,but also greatly influenced the fast exhumation of metamorphic rocks in Dabie Mountains.