Abstract Promotion of private participation is catalogized as concession model of construction means. The process is the authority to select the private sector that has the best professional knowledge and capability and to transfer the properties to the selected private sector and confer the private sector the concessionary. The private sector then is responsible to finance, construction, operation during the concessionary period. The revenue of the operation and the ancillary business that concessioned by the government will cover the cost of operations and construction. After the concession period, the rights and operations will be transferred to authority. The spirit of private participation is in the process of the private participation. The involvement of private sector injects the flexibility and energy that the government lack of. The private sector also shares the cost of construction that is some financial burden of the government. For this kind of approach, the private sector needs more flexibility and own operations freedom and shares most of the risks. As for the supervision of the government, in general, the less the better. Because the private sector makes its own construction and operations strategies and sales management. In other words, the private sector shall has the independence. The interference of the government shall be limited to minimum, even for the public interest, to prevent the incompatibility of the two sectors and the negative effect of the promotion of the public construction.. However, the supervision logic is excluding the cases that the government financing most of the cost and the interest of the public. This paper argues that the public construction with private participation approach shall be case dependent, from the administration point of view. For the high public interest and high financing project, The government based on his authority and responsibility shall be supervised intensively to ensure the quality and safety of the public construction. One of the issues that the paper raised is the supervision role of the authority. This paper argues how the authority to be a good supervisor. How the authority does his responsibility and accomplish his mission and take appropriate measures to ensure the good quality of the public service continuously. For research methodology, the reference analysis is adopted. The theory and system of private participation are discussed. As for case study, reference and interview are adopted. The supervision and management of private participation of Kaohsiung mass rapid transit by government is analysed to bridge the theory and practice. The characteristics of this project is low self-financing rate. The government financing the rest part of the cost, which is about 80%of the cost. In this project the government also guarantees the forced buy out price, which states clearly in the tri-party contract. This make the financial risk is all on government. The way of taking risk is more likely the OT approach. From the interview, the implementation of the project reveals that anti-supervision game, multi-supervision and management system. Also the different sectors has different understanding of the project. The legal position of the supervision role of the authority is the legitimate to supervise and take appropriate actions. The public sector acts according to laws and safeguards the public interest. The authority has the righteous to supervise, the legal stance. Another role of the authority is also the party of the contract to protect his interest in his investment, which is stemming from the contract, the legal rights from the private sector. During the construction and operations period, the authority shall review and supervised. The legal measures for authority includes the supervision of operations, the restrictions of concessionary, the dispositions of the assets of the construction and operations, The review of the operations fare and changes. The rights stemming from contracts includes setting the standards of the operations facility, the review of the design drawings and schedules and construction quality and subcontracting, the public tendering of parts of the governments financing. For the combinations of both supervision measures includes financial supervision and the acceptance of important contract subcontracting. If the delay of schedule, serious construction quality, serious operations problems, and breach of contract happens, the authority, for the public interest, shall coerce request the private sector to amend in due time, stop all or part of construction and operations abolish the permissions of construction and operations or coerce takeover operations or buyout to ensure the project. As for the rights stemming from contract includes risks sharing, the conditions that the intervention of the financing institutions, suspending all or part of the construction or operations, cease of contract, insurance and bond, mechanism of loyalty and fund. In this study, the legitimate of the supervision role of the authority is discussed and aims to have a robust structure of private participation of public construction system to achieve the goal of promoting public service standard and accelerating development of social economy when promoting privatization of public construction.