This paper discusses biomarker geochemistry in low grade metamorphic source rocks of the Mohe Formation, Mohe Basin. The mainly object is to describe redox conditions and salinity of depositional environment and source of organic matter and thermal evolution of the source rock. The results showed that: (1) The carbon number distribution is C11~C27 and main peak is C17 of saturated hydrocarbon. ∑C21-/∑C22+ is between 4.0 and 6.3, with the average being 5.3. OEP is between 1.23 and 1.37, with the average being 1.31. Pr/Ph varies from 0.9 to 1.4, with the average of 1.2. The variation of gammacerane index from 0.23 to 0.30 and an average of 0.27; C35/(C31~C35) homohopane between 0.04 and 0.06. (2) The relative content of hopanoid is the highest, followed by tricyclic terpane, the relative content of tetracyclic terpane is the lowest. The relative abundance of the regular steranes C29 has the highest values, C27 by the second and then C28. Regular steranes show a pronounced “V” type of C27-, C28- and C29- components. (3) The contents of diahopanes and rearranged sterane are relatively low. The contents of β-carotane, oleanane and 25-norhopane have obvious mean peaks characters. Based on the analysis of multiple biomarker geochemistry and the depositional environments and tectonic evolution feature, we have drawn conclusions that: the source rocks in the Mohe Formation were deposited in relative high salinity and strong reducing environment of the lacustrine face, organic matters are characterized by mixed origins from higher plants and aquatic organisms, and they are mainly during the high-mature stage.