Extant studies of environmental investment determinants have not distinguished between different types of political connections. This study tries to close this gap by employing an extensive dataset based on the four-yearly Chinese Private Enterprises Survey conducted between 2006 and 2012. The central question in this paper asks whether different political connections (ascribed vs. achieved) are fostering or hindering environmental protection expenditures in private enterprises. The results show that achieved political connections serve as binds of promoting firm environmental investment while ascribed political connections act as buffers, hampering firm environmental expenditures. The moderating roles of environmental regulation and innovation capability demonstrate heterogeneous effects: environmental regulation stringency strengthens the positive impact of achieved political connections only. In contrast, innovation capability enhances the negative impact of ascribed political connections.