Abstract: From the viewpoint of organic petrology, combining kerogen method with bulk rock, this paper classified the organic macerals of Yanchang formation high-quality source rock in Ordos basin into 4 groups as follows: sapropelinite, exinite, vitrinite and inertinite. The classification is based on petroleum industry standard and takes account of the characteristic that the optical variance of the hydrogen-rich macerals is obvious during the thermal evolution at the same time. As the most primary maceral of Yanchang formation, the sapropelinite indicates that lake alga is predominant parent material. In addition, it is confirmed that the existence of sapropel particulate vitrinite means deoxidized depositional environment and intense micro-degradation, as well as that high-quality source rock has entered remarkable hydrocarbon-generating stage, which offers evidence for classification of thermal evolution stage of organic matter.

Key words: Ordos basin, premium source rock, maceral, microsome