Abstract: Kedao Group is distributed in Kaishantun-Wangqing area at the east end of Changchun-Yanji tectonic zone. The out-cropped Kedao Group in Kaishantun area lacks fossil basis, and hence its age assignment is still in doubt. In this study, representative samples were collected in the upper and lower part of Kedao Group, and the detrital zircon U-Pb (LA-ICP-MS) dating was con-ducted. The ages of the upper fine detrital zircon are 252～2304Ma and those of the lower crude detrital zircon are 260～713Ma, re-spectively forming two similar peak ages. The former two peak ages are 263±2Ma and 460±4Ma whereas the latter two peak ages are 266±3Ma and 463±4Ma, suggesting that clastic sediments were mainly derived from the geological body of Ordovician and Permian. The youngest zircon is 252Ma in age while the rest ages relative to the youngest zircon ages are concentrated in Early Late Permian. According to combinational sedimentary formation assemblage characteristics of Kedao Group and regional correlation, it is conclud-ed that the age should be Early Triassic, and they are intermontane quasi-molasse sedimentary rocks due to the rapid uplift of the oro-genic belt after the closure of the Paleo-Asian Ocean.