For the complicated fault -block reservoir influenced by lithology, the distribution of remaining oil is relatively complicated in middle to late periods of oilfield development. Reservoir numerical simulation method is an effective measure to quantitatively study on remaining oil distribution in this kind of reservoirs. On the background of deep Gaoshangbao reservoir and according to the result of fine reservoir description, the 3D reservoir geological model is established. Then the key point and difficulty can truly be understood. Based on the history match of the reservoir performance, the adjustable parameter and its limit are figured out. At last, the distribution rule of remaining oil, the distributed types of remaining oil and the factors affecting remaining oil distribution can be obtained.