The study conducted geochemical analyses of mudstone, siltstone and sandstone samples from the Yushulin Oilfield, Sanzhao sag. The results show that the most of major elements have moderate contents. Compared with the average of upper continent crust (UCC), the samples have lower Fe2O3, MgO, CaO and Na2O, but slightly higher TiO2, Al2O3, K2O, MnO. The contents of compatible elements (V, Cr, Co and Ni) in the samples are lower than PAAS (Post Archean Australian shale) and UCC, and the total amount of REEs ranges from 102×10-6 to 276×10-6 with an average of 188×10-6. The similar chondritenormalized REE pattern with PAAS suggests that they have similar provenance and tectonic settings. The Pearson correlation of some elements shows that most elements are negatively related to SiO2 but positive to Al2O3, indicating that most elements are affected by clay minerals because quartz and feldspar exert a dilution effect on these elements. Based on the provenance discrimination diagram of major elements, ThHfCo plot, and La/Hf and (Gd/Yb)N, it can be concluded that the provenance of studied area mainly derived from felsicpredominant rocks, probably involved in some recycle sedimentary rocks. A series of tectonic discrimination diagrams suggests that the Fuyang oil layers deposited in a continent island arc setting. Paleclimate analysis of oil sublayers shows that FI sublayer deposited in a strong tectonic activity settings and drought climate and is of better reservoir physical properties. Therefore, this should be the key layers for oil and gas exploration.