Abstract: The detrital zircon U-Pb geochronology of the Late Paleozoic strata in Horqin Right Wing Middle Banner was studied in this paper. Sample 130909-01 and 130910-15 were tuffaceous sandstone and lithic quartz sandstone samples, respectively. The detrital zircon ages can be divided into four groups: 252~278Ma, 286~359Ma, 381~462Ma and older than 500Ma. The youngest zircon age (256.5±1.7Ma) constrains the maximum sedimentary age of the Late Permian. A large number of relict zircons were existent in the samples, which kept a record of Precambrian basement, early Paleozoic arc magmatic rocks and magmatic activity event during Permian-Carboniferous period.