Abstract: Based on the genetic study of low-mature oil,the results of simulation experiments and the natural evolutionary profiles of organic matter,it is pointed out that low-mature oil is in fact a by-product during the diagenetic evolution of organic matter.In the diagenetic stage,the production rate and cumulative production rate of low-mature oil generally have on hydrocarbon-generating (or oil-generating) peaks with the increase of maturity.This is distinct from the hydrocarbon-generating (oil-generating) pattern of kerogen in the plutonic stage of organic matter.The hydrocarbon production rate and cumulative production rate of low-mature oil mainly depend on the original hydrocarbon content in primary mother material,the hydrocarbon trapping during the formation of kerogen,the low-temperature decomposition of part large geologic moleculars,the components of rock mineral and other factors.In this paper,the popular hydrocarbon-generating (oil-generating) patterns of low-mature oil are supplemented and modified.