If no fatal events cause structure and nature of risk to change, we can research on risk evolution of large PPP projects with nonlinear regression method. There are three influence factors which are macroscopic environment, micro environment, subject's capacity and their cooperative relationship. This research has three steps. Firstly, it finds out the three main drive variables of project risk evolution through case analysis. Secondly, it builds non - linear time - varying measurement model and transforms it to classical regression model. Las...