Abstract: A precise Re-Os age is given for the Langyashan copper deposit in Chuzhou. The model age for five molybdenite samples from the deposit varies from (128.9±1.8) Ma to (130.3±1.9) Ma and the isochron age is (128.6±2.2) Ma, MSWD=0.45. The results indicate that the origin of the deposit is from regional tectno-magmatic activities during the early cretaceous period. The molybdenites from the Langyashan copper deposit have a very high Re content, which indicates that the deposit originated from the mixing of the crust and the mantle sources with the mantle as a primary source.