Objectives:The granites in central Qiangtang have important geological significance, which not only constraints the evolution of Longmuco—Shuanghu Suture belt, but also the onset of Qiangtang Jurassic marine basin. Combined with zircon geochronology, geochemistry and Hf isotope, we briefly discuss the geological significance of the Baicuo granites.Methods:Based on the field work, through the microscope observation, the zircon geochronology, the whole rock chemical analysis, Hf isotope analysis of Baicuo granites.Results:The Baicuo granites in central Qiangtang show that the pluton is a composite batholith placed by granodiorite and monzogranite. The zircon U- Pb ages are 213.8±1.3 Ma, 210.0±1.1 Ma and 208.1±1.4 Ma, respectively. The Baicuo granites have typical characteristics of crust source, with enrichments of large ion lithophile elements (LILES) and depletion of high field strength elements (HFSEs), as well as exhibiting obvious Eu anomalies. The εHF(t) is negative, mainly concentrated in -10~-15. The corresponding two- stage model age (TDM2) varies between 1.66 Ga and 2.17 Ga, which indicates that the source region is from the Paleoproterozoic ancient crust. The dark xenoliths maybe indicate magma mixing, which is caused by the injection of mafic magma into felsic magma. The Granites formed by basaltic underplating and full melting, intruded along the existed structural fracture zone in central Qiangtang.Conclusion: The granites and the coeval bimodal volcanic rocks are the products of the same rift dynamic mechanism. The intrusion of granites indicates the end of the tectonomagmatic activities in the Late Triassic Qiangtang basin, and the onset of the Jurassic Qiangtang marine basin.