The relationship between the thirdparty logistics (TPL)and supply chain is a typical embedding relationship，but the theoretical basis of TPL embedding in supply chain was not studied. This article studied the motive of TPL embedding in supply chain within Sociology, Economyics and Management’s perspective. And the article draws some conclusions, the embeddedness theory provides a trust basis of TPL embedding in supply chain, and the social network theory studies the network structure and relationship evolution of TPL embedding in supply chain based on weak ties and structure hole. Transaction cost theory points out the purpose of TPL embedding in supply chain is saving transaction cost. In addition, system economy theory indicates TPL embedding in supply chain is the results of the combined effects of division and cooperation. Principalagent theory explains the stability of TPL embedding in supply chain based on trust relationship and incentive mechanism. At last, Core competence theory explains the direct reason based on logistics outsourcing and alliance.