Abstract: In this paper, infrared spectrometry is used in probing the organic matter type of source rocks from the 1st member of Qingshankou Formation, Cre-taceous in Songliao Basin and Yanghugou Formation, Middle Carboniferous in Upper Paleozoic, Taiyuan Formation of Upper Carboniferous and Shanxi Formation, Lower Permian in Ordos Basin. Meanwhile, it presents the structure ratio of alkyl/aryl (ER cm¹/EAr cm¹ which can be taken as an indicator for identifying organic matter type.