Abstract: In many researches on distribution rules of residual oil, we often describe qualitatively what the saturation of residual oil distributes in the whole reservoir according to the character of distribution in space. To accomplish it, we shall make use of logging data. However most of researches don't analyze it quantitatively, and there are scarcely quantitative forecast to the distribution of residual oil about every tiny layer in every well. This paper carries out it with quantitative forecast. On the basis of the productive data of Xiaermen Oilfield, it discusses something on establishment of the saturation of residual oil allocation method, such as origin, process, and condition when it was adopted. On the other hand, some conclusions on distribution of residual oil can be drawn according to the result, and it will lead the way to exploitation in the future. By calculating in every tiny layer, we can get the quality and saturation of residual oil. It gives the base of studying the distribution of oil in the plane and vertical. In addition, by combining the static data of oilfield (such as porosity and permeability), we also study the control factors of distribution of residual oil. So it is useful to the further study of oil production.