Abstract: During the 1:50000 regional geology survey of Tuituan and other three sheets in Jilin Province, the longdebated pre-Mesozoic strata are re-divided into Xinxing rock formation and Hongshan formation on the basis of detailed field geological survey and previous achievement. Furthermore, with LA-ICPMS, the U-Pb age of clastic zircons in the clastic rock is dated, showing that the deposition of Hongshan formation began in Late Permian, which offers a meaningful reference to further study on the deposition time of orogenic metamorphic rock.