Objectives: Eastern detachment fault zone of Lushan metamorphic core complex has recorded the early sinistral strikeslip ductile shear structures of Ganjiang fault and the late extension—detachment structures of Lushan metamorphic core complex. Therefore, whether Lushan metamorphic core complex is the product of the property’ transition from compression to extension under Pacific tectonic regime becomes a doubt. If this is the case, the problems about geological evidence, transformational time and mode all deserve our further inquiry. Methods: These samples of pegmatite vein and felsic vein were collected from extension—detachment rocks within eastern detachment belt of Lushan metamorphic core complex, with its geographical coordinate of N29°26′58″, E116°00′58″. Zircons were separated using standard magnetic and heavyliquid techniques at Langfang laboratory, Bureau of geology and mineral prospecting and exploitation of Hebei province. Cathodoluminescence (CL) images were made at Jinyu Technologies Co Ltd, Chongqing. Zircon U-Pb dating was conducted using a GeoLasPro LA-ICPMS coupled to a ArF 193 nm ultraviolet laser system with 32-μm-diameter beam spot at School of Resources and Environmental Engineering, Hefei University of Technology. The standard zircon 91500 and SRM 610 were used to calibrate the Pb/U ratio and U concentration. Analyte signals, timedrift corrections, and quantitative calibration of trace element analyses and U-Pb ages were performed using the in-house software ICPMSDataCal9.0. The measured Pb isotopic compositions were corrected for common Pb using non-radiogenic 204Pb. Uncertainties for individual analyses (ratio and ages) are at level 1r. Results: Most of the zircons can be divided into two types, and palingenetic zircons crystallized from metamorphic fluid record young mean U-Pb ages of 136.4 ± 2.1 Ma and 139.1 ± 1.6 Ma; relict zircons inside crystallized from hydrothermal alteration record older mean U-Pb ages of 150.5 ± 3.6 Ma and 153.9 ± 4.5 Ma. We infer that the ages of 136.4 Ma and 139.1 Ma represent the extension time of detachment belt, eastern Lushan metamorphic core complex, while the ages of 150.5 Ma and 153.9 Ma represent the time of sinistral shear deformation. Conclusions:Controlled by Pacific tectonic regime, this region was in the tectonic setting of compression with sinistral shear structures due to Pacific plate’ subduction obliquely during Late Jurassic to Early Cretaceous. Then the compressional stress transformed into extensional stress under lithospheric extending and thinning with the formation of Lushan metamorphic core complex in Early Cretaceous. In a word, the early sinistral shear structures were modified and overlaid with the extension—detachment structures.