Abstract: The biomarker characteristic indicates the sources of organic matter, sedimentary environment and the thermal evolution of the source rocks. the analysis of the source rocks of Ganquan Formation of lower Permian-upper Carboniferous and middle lower Permian system in Mengecan 3 well of Jigeda sag by GC and GCMS shows that, the peak range of n-paraffins of the source rocks of the lower Permian-upper Carboniferous upper Ganquan formation and middle lower Permian is wider. The light-component in the saturated hydrocarbon component of the extracts is larger than the heavy one. Low carbon hydrocarbon dominates. Terpenes are mainly tricyclic ones and the content of tetracyclic terpenes is low. The organic matter of Carboniferous-Permiansystem source rock is mainly plankton, and some contributions of higher plants, while the Carboniferous has more plankton and less land-higher plants. OEP and CPI indicate that the source rocks of Ganquan Formation and middle lower Permian are even-odd potential and in a mature stage. the degree of evolution of Carboniferous is slightly higher than middle lower Permian. The distribution characteristics of Pristane and phytane show that the source rocks of upper Ganquan Formation are in a reducing environment, and those of the middle lower Permian are in a strong reducing- reducing environment.