Abstract: In order to enrich and improve materialistic conception of history, Marx and Engels attached great importance to family thought of the primitive society and conducted in-depth study and elaboration. Family theory is the evitable content of materialistic conception of history in Marxism principles. In “Dialectical Materialism and Historical Materialism”, Ai Siqi specifically explains the family ideas of Marx and Engels. Summarizing the outcomes and deficiencies of his family theory has important theoretical and practical significance for restoring the development history of materialistic conception of history and enriching family conception of history of Marxism