The investment decisions of private enterprises play an important role in mobilizing social capital activity and promoting economic development in emerging economies. The existing research literature mainly focuses on external environment, internal resources, and other aspects, and rarely explores the willingness of private enterprises to cooperate in investment from the perspective of policy uncertainty in the process of government and social capital cooperation. In addition, although some scholars have studied the policy uncertainty of the government, there has been little in-depth research on the policy uncertainty of PPP, no establishment of a central and prefecture level city text lexicon, and a lack of a complete measurement system and quantification process. Based on cutting-edge research literature and directions, this project intends to focus on exploring four issues. First, what is the connotation of PPP policy uncertainty? Second, how does policy uncertainty affect investment confidence and subsequent cooperative investment of private enterprises during the cooperation process? Third, does the environmental characteristics of the location of private enterprises have a moderating effect on incentivizing investment? Fourth, what are the spatial spillover effects of local policy uncertainty on investment decisions of private enterprises? These issues have clear leadership and pioneering significance in the fields of corporate behavior research and PPP research.