Abstract: A number of sandstone-type uranium deposits have been found in the Lower Cretaceous Saihan Formation of Erlian Basin. The segmentation of the Saihan Formation has impact on exploration to some extent. Core observation, logging, seismic profile and comprehensive core documentation show that the Saihan Formation can be divided into four intervals, i.e., Ⅰ(K1bs1), Ⅱ(K1bs2), Ⅲ(K1bs3) and Ⅳ(K1bs4). K1bs1 consists of variegated coarse-grained clastic rocks deposited in alluvial fan. K1bs2 consists of gray or dark gray or dark mudstones and coal beds deposited in swamps and muddy lakes. K1bs3 consists of gray coarse-grained clastic rocks like conglomeratic sandstones deposited in a braided river environment. K1bs4 consists of yellow sandstones interbedded with red mudstones deposited in a meandering river environment. The target layer for sandstone-type uranium mineralization is interval Ⅲ in the Manitesubbasin and interval Ⅳ in the Wulanchabusub basin. No uranium mineralization has been discovered in intervalⅠ and Ⅱ up till now.