Hydrocarbon carrier system is important as“the bridge and vinculum”between the oil sources and traps in hydrocarbon accumulation. Based on previous study，hydrocarbon carrier systems were studied through analyzing the migration mechanism. The results obtained show that the hydrocarbon migration mechanism is in essence hydrocarbon migration in space，which includes carriers，driving force and their intrinsic links and evolution. The naming principles of hydrocarbon migration classification were put forward as key migration period，transportation direction，driving force and transportation space，which can be used in the effectiveness evaluation of hydrocarbon carrier system and the prediction of hydrocarbon reservoir distribution to provide guidance for hydrocarbon exploration. As a case of the southern slope in Dongying sag，the hydrocarbon carrier systems formed at the end of the Minghuazhen Formation sedimentary period are divided into 3types，which are the end of the Minghuazhen Formation sedimentary period-vertical migration-middle to high pressuremiddle porosity hydrocarbon carrier system，the end of Minghuazhen Formation sedimentary period-lateral and vertical migration-middle to high pressure-large porosity hydrocarbon carrier system and the end of Minghuazhen Formation sedimentary period-lateral migration-middle to high pressure-buoyancy-large porosity hydrocarbon carrier system.