The orientation, objectives, activities and adaptability of Internal Audit (IA) have changed a lot as a response to the rapid change of operational environment and the complexity of risks. And the trend that IA has being transited to value-added IA reflects these changes comprehensively. After reviewing and referencing some beneficial parts of the models represented in Value Proposition of Internal Audit and The Three lines of Defense in Effective Risk Management and Control, as well as the Internal Audit Capability Model (IA CM) for the Public Sector of IIA, this paper builds the basic operation mode of value-added internal audit, and presents some development strategies in transitional period of IA. It concludes that the IA needs explicit understanding about its position and role in governance structure, paying close attention to the appeals of stakeholders, recognizing the challenges in complex business environment and dealing with it properly. In addition, IA should stay focus on their assurance services, while improving the consulting services, enhancing the human resources and IT skills and caring about the shaping of corporate ethics and values as well.