The PPP construction mode has the advantages of reducing the financial pressure of the government, improving the efficiency of project construction and operation, and risk sharing, and can provide key proporty and professional support for urban infrastructure and widen the social capital investment channel. In this paper, the first urban infrastructure constructed by PPP mode in China, Honggu Tunnel in Nanchang, is taken as an example; and then the applicable effect and existing problems of PPP financing mode to urban infrastructure construction and operantion are analyzed. The study results show that by adopting PPP model, the construction of Honggu Tunnel has been promoted, the investment, construction schedule and quality of the project have been effectively controlled and good effect during operation period has been achieved.