The problem of local government debt has been serious over the past several years in China,PPP model is a new direction for the construction of infrastructure. As the most important financing institute, commercial banks are bound to play a larger role in PPP projects.We first introduce the meaning and three parts of PPP.Then classify the risks of PPP model.Next we discuss the risk sharing model among government,private sectors and banks using game theory.At last,we recommend to banks about preventing risks when the participate in PPP projects.