The uncertainty of infrastructure investment policy is a peculiar phenomenon in China, which is not conducive to the stable and sustainable development of the infrastructure investment market. However, there is no systematic analysis of this phenomenon in the literature. This article summarizes the 1337 central-level and infrastructure investment policy texts from 2014 to 2021, analyzes the inter-government relationship network behind the uncertainty of infrastructure investment policies by using Policiometrics methods, and constructs the infrastructure investment policy uncertainty index in China by text-mining. The study found that: first, the uncertainty of China’s infrastructure investment policy is characterized by irregular fluctuations, and is strongly related to the volatility of the infrastructure investment market; second, the cooperation network of the issuer of the infrastructure investment policy presents a “ternary center” pattern, which is still evolving in time trends. Coordination failure between departments is one of the internal causes of policy uncertainty. Finally, the uncertainty of infrastructure investment policy is affected by the external environment and is transmitted to the local government during the implementation process. Clarifying the formation mechanism of infrastructure investment policy uncertainty will help improve the inter-sectoral coordination mechanism in China and achieve effective governance of the infrastructure investment.