This paper is a review for the concepts，genetic classification and application of petroleum system. All the geological elements and processes as well as their history which are essential for hydrocarbon accumulation forming are treated as an organic system to study in petroleum system，the volume and potential of souce rock and hydrocarbon shows are the most important aspects on petroleum system analysis.
    There are three important factors-charge，migration drainage style，and entrapment style in a petroleum system，which are the foundation of genetic classification of petroleum system.
    Petroleum system is a useful tool in evalution of oil and gas prospect，which had been successfully used.Petroleum system is one of important subjects in petroleum geology recently.