The sedimentary course controls the distribution of minerals and source rocks. The characteristics of source rocks in the Member 3 of Shahejie Formation in Dongying Depression revealed the obvious fluctuation of the sedimentary course of lake. Tectonic movement controlled the rise and settle of the whole lake, and with the influence of climate and the other geological factors, the lake deposit was a result of complex sedimentary course which was a main sedimentary cycle contained many hypo-cycles. The heterogeneity and the unstable deposition in the stable deposition of source rocks were believed as a result of the lacustrine cyclothemic sedimentation and the Jake-level fluctuation. The environment of deep water-body and high salinity in the Member 3 of Shahejie Formation was characterized by high content of many trace elements and high value of B/Ca, Sr/Ba. The deposition in fluctuation contributed to the distribution of organic matter in different manners; organic matter was enrichment in the lower part of the Member 3 ol Shahejie Formation, and it was source rocks in high quality; the organic matter was dispersed in the middle part of the Member 3 of Shahejie Formation, whose resource potential for hydrocarbon generation and expulsion was restricted.