Abstract: Sandstone reservoirs were predicted so as to propose a new method for the studies of reservoirs with complicated lithology in saline lake basins. The study area was the semi-saline period in the oil group no.0 in the fourth member of the Paleogene Qianjiang Formation (E_2q4⁰) in areas W, G, and H in the Qianjiang Sag of Jianghan Basin. The method was called "four-definition", which defines sedimentary facies through integrating geologic data with seismic data, defines markers through petrophysical modeling, defines geological boundaries through comprehensive multi-attribute geological analysis, and defines stratigraphic thicknesses through definitive inversion. Applications in the Qianjiang Sag succeeded in finding several high-yielding oil pools of beach bar facies, showing that the method can improve the prediction accuracy in reservoirs with complicated lithology.