Abstract: In this paper, the stratum and fossil assemblages of the well Lunnan—1 in Tarim Basin, Xinjiang, are systematically described . The Mesozoic stratum in this well has been divided in descending order as following： The Kapushaliang Group (K_1kp)， the Qigu Fm, (J_3q)， the Qiakemake Fm.(J_2q²) ， the Kezilenur Fm. (J_2k)， the Yang xia Fm. (J_1y) and Arhe Fm. (J_1a). Based on the correlation of lithological and mineral features between this well and the Kuche depression and plant fossils, the depth from 4825m to 5039m in this well us identified as the Lower Jurassic Arhe Fm., and also a brief discussion on the age of the fossil sporo- pollen assemblages found from this well depth is given.