Abstract: The working area in this article includes Linnan Sag and its surrounding areas. Oils with industrial value found at present all come from the Es3 Member located in depth of Linnan Sag. The sedimentary environment of the Es3 Member in Linnan Sag is deep to semi-deep lake facies with a condition of weak oxidation to oxidation. The content of oleanane detected in most samples shows that the source of organic matter has an input of high plant and the ratio of high plant to aquatic organism varies with the sedimentary facies of Es3 Member. In the water of south part pyrrophyta is more abundant. 　　The oil in Quti uplift has been subjected to light biodegradation and water washing in depth. Biodegradation and water washing did not affect the oil from Linnan oilfield. Oil from Qian-Guantun Structure is not affected by biodegradation also, but has a very low content of aromatics because of water washing. In Linpan oilfield only oil from the Guantao Formation suffered light biodegradation. 　　Although all oil from Linnan area has a common source, i.e. Es3 Member in Linnan Sag, some differences exist between oils from Linnan oilfiled, Quti oilfield, Linpan oilfiled and Shanghe oilfiled, etc. Therefore these oils can be divided into different origin types. Three types of oil are recognized, i.e. Linpan-Shanghe type, Linnan type and Quti type, according mainly to 4-methyl sterane content and also based on light and medium hydrocarbon composition and other biomarker characters of oils. 　　Two oil source areas，i.e. north part and south part oil source area， are recognized according to the results of comparison of oils and its source rocks and composition analyses of liquid inclusion enclave. The former has two stages of oil formation and expulsion and is the source of oil with lower 4-methyl sterane content and accumulated in Central Uplift. The later has only one phase of oil formation and expulsion and its oil has a high maturation level and a higher 4-methyl sterane content. 　　The system that can form industrial oil accumulation is called effective oil migration and accumulation system in this article. Four such systems are recognized. The system Ⅰ is formed at the end of Oligocene, its oil has a low 4-methyl sterane content and accumulated in Linpan and Shanghe oilfield. Other three systems are all formed during the peak period of oil formation of Es3 Member by the end of Miocene. The system Ⅱ also contributed to Linpan oilfiled with oil having low 4-methyl sterane content, the system Ⅲ formed Linnan oilfield and Qianguantun oil pool with oil having high 4-methyl sterane content, and the system Ⅳ resulted in Quti oilfiled with oil from both north source part and south source part and having medium 4-methyl sterane content. 　　According to the characters of all four systems and current level of exploration in Linnan area, the most favorable exploration area is Quti Uplift.