Recently, the focus of IT outsourcing has been shifting from the "what" and "why" issues to "how" companies manage outsourcing process, during which the relationship management becomes vitally important for the overall success of IT outsourcing. Simultaneously, trust, as a component of relationship, plays a central role in the success of IT outsourcing relationship. In view of these, this paper will explore the role of trust in successful relationship management, and further in the ultimate IT outsourcing success. The paper will also contribute by categorizing trust into two levels-organizational level and individual level, and exploring especially the effects of interpersonal trust. Knowledge sharing as a risk taking behavior will mediate the path from trust to relationship success. Theory of Organization Boundary Systems and Social Exchange Theory will be used in the model building process, and a survey will be conducted to test the model empirically.