Public-Private Partnership (PPP) model is an important measure for transferring government functions and promoting socialist market economy in China. After four years of high-speed development and standardized development in recent years, PPP model has achieved good effect in our country. However, multiple problems emerged. In China, the “public” party of the model has always been dominated by state-owned enterprises. Although private enterprises have the willingness to participate, the actual participation degree and volume are not high which is not good for the sustainable development of the PPP model. This paper applied grounded theory to carry out in-depth interviews with the representatives from government, private enterprise, and SPV company in some key PPP projects with private participation, propose four coral categories to construct the whole process of private enterprises’ participation and summarize the behavioral features, and explore private enterprises’ realization of their participation willingness into actual participation behavior and the generation of their continuous participation willingness so as to clear the private enterprises’ participation path in PPP projects.