The sediments-hosted base metal deposits controlled by Cenozoic thrust-nappe structural system in Lanping Basin, southwest China, apparently differ from the sediments-hosted base metal deposits in other parts of the world. The Liancheng vein-type copper deposit is one of these deposits in Lanping Basin. In this study, the Re-Os isotopic dating method was used to measure 6 molybdenite samples collected from the Liancheng copper deposit. The isotopic model age is(48. 14±0. 87) Ma and the isochronic age is(49. 0±1. 3) Ma, indicating that the deposit was formed at 48~49 Ma. This result also suggests that the copper-silver ore-forming system in western Lanping Basin was formed earlier than the lead-zinc ore-forming system in eastern Lanping Basin.