A study of various geochemical parameters indicate that crude oils in the Ku che petroleum system have both marine oils and nonmarine oils，with the latter predominating in the system.In marine oils，pristane show slight dominance，with the pristane to phytane ratio less than 1.50. The content of drimane is higher than homodrimane，and thier rearranged compounds are low in these oils.There is high content of tricyclic terpanees， and C23 is the highest peak.These oils have low pentacyclic triterpanes contents，and the content of C29TS compound and Ｃ*30diahopane is not high.In contr ast，in nonmarine oils，pristane shows significant predominance，with the pristane and phytane ratio more than 1.50.The content of homodrimane is more higher than that of drimane，and thier rearranged compounds are abundant in these oils.There is a low content of tricyclic terpanes， and C21 is the highest peak.These oils have high pentacyclic triterpane contents，and the content of Ｃ29TS compounds and Ｃ*30 diahopane is abundant. The Carotane compound series，with a higher abundance，has been determined in both marine oils and nonmarine oils.