Abstract: By using the method of historical materialism and starting from the human practic, Marx establishes the domain of social divisions scientifically, gives a demonstration of the inevitability and the rationality of social divisions, divides the historical phases of the social division development and elaborates the great effect of social division on the development of society and human race. We should understand the theory fully and correctly because it is significant both in theory and reality to implement the scientific concept of development, to build a harmonious society, and to promote an all-round development of the human race.