Abstract: This paper selects the lithology?sensitive natural gamma, neutron, density and acoustic logging curves to establish lithology identification cross?plot for Lucaogou tight reservoir in Malang sag of Santanghu basin, and identifies 12 kinds of main lithology, including mudstone, tuffaceous shale, calcareous mudstone, argillaceous dolomite, etc. The study shows that the tight reservoir of Lucaogou formation is mainly controlled by the lithologic combination, of which the mudstone intercalated with (thin) calcareous mudstone and dolomitic mudstone or the lithology dominated by calcareous mudstone and dolomitic mudstone is the most favorable lithologic comnination, and the oiliness is the best