Abstract: In addition to the main Permian magmatic activities and a few Precambrian magmatic activities occurred in Tarim Basin, there is still lack of conclusive evidence that any magmatic activities happened in other times.This paper reports SHRIMP zircon U-Pb ages of diabase from the well shunbei-1 in Upper Ordovician Sangtamu Formation of Tarim Basin.The zircon U-Pb dating show that these diabases have age of (444±3)Ma, belonging to Upper Ordovician.In combination with seismic profiles and previous geochronology,this intrusion was considered to be the product of the mantle-derived basaltic magma intruded into the shallow level, which was resulted from the subduction and collision between West Kunlun-Altyn oceanic basin and the southern margin of Tarim plate.