1. Information Center of Geology and Mineral Resources of Jilin Province，Changchun 130061，China; 2. The Sixth Geological Survey of Jilin Province，Yanji 133001，Jilin，China

The geological characteristics of Jidetun and Shimadong large molybdenum deposits are reported． Re- -Os isotopic dating of molybdenite shows that the Re- -Os model age of Jidetun molybdenum deposit is from (168. 79 ±0. 42) Ma to (169. 91 ±0. 47) Ma，averaging of 169. 31 Ma，with the isochron age of (169. 1 ±1. 8) Ma (MSWD =7); the age of Shimadong molybdenum deposit is from (164. 85 ±1. 46) Ma to (166. 21 ±0. 90) Ma，averaging of 165. 66 Ma，with the isochron age of (169. 3 ±1. 9) Ma ( MSWD =1. 3)． These ages indicate that the molybdenum deposits formed in Middle Jurassic，which consistent with the forming age of Daheishai molyb- denum deposit and its contemporary ones． According to the geochronologic data obtained，it is assumed that the molybdenum mineralization in centro- eastern Jilin largely took place during the Early- Middle Jurassic． Based on the analysis of regional tectonic evolution，deposit characteristics and petrologenesis and metallogenesis ages，it is con- sidered that the large- scale molybdenum mineralization in centro- eastern Jilin was closely related to the intensive subduction of the Pacific Plate to Eurasian Plate．