Abstract: Complex fault block reservoirs are the main reser-voir types in Xianhe and Dongxin oilfields where the dis-tribution of residual oil is complicated after long period development and several development adjustments.Quan-titative and qualitative description of the residual oil in the reservoirs is performed in this paper by using com-bined static and dynamic analytical method,sedimentary microfacies method and numerical reservoir simulation technique.The impacts of geology,water-driving mecha-nism and development on the distribution of residual oil are also analyzed.Study results were applied in compre-hensive development adjustment leading to production up while composite water-cut down and a4.2%higher oil recovery.