Abstract: Based on a comparison from the results of optical characteristics, vitrinite reflectance, elements analysis, concentration of free radicals, infra red spetrum analysis and pyrolysis chromatographic analysis between those from 2 kerogens from paleo-green algae and those from the insoluble organic matter (kerogan-analogous) derived from the pyrolysis of a modern green algae. It is found that the both type I kerogen and kerogen-analogous of Blue green algaes at low maturation stage are characterized by very high O/Cratio(0.25) and very low H/C ratio(0.6). This paper suggests a new idea which is different from type Ⅳ krogens suggested by Tissot. Van Krevelen diagram and the concept of type Ⅳ kerogens cannot be applied to the highly maturated Blue green algae kerogens with these special features; they still have the possibility of hydrocarbon generation along a source specific process of evolution.