The Impact of Multiple Policy Mixes on Urban Green Innovation: Evidence from China

In the context of an increasingly tense relationship between environmental and economic goals, green innovation is of crucial importance for the global green transformation. However, its dual external effects often render a single policy tool ineffective, which makes the implementation of a policy mix necessary. In this study, according to a three-dimensional policy mix framework, four pilot policies in the fields of environment, innovation, and finance were selected and combined in pairs. Panel data from 276 Chinese cities (from 2006 to 2021) were used to compare the differences in the effects of different types of policy mixes on green innovation using the difference-in-differences method and to verify the mediating effects of green finance and university–industry collaboration. The synergy test results show that the cross-domain mix with the differentiation of tool types and the compatibility of mechanisms is the best. The policy effects were more evident in cities outside the Yangtze River Economic Belt and in non-central cities. These findings provide theoretical and practical insights for designing an effective policy mix to promote green transformation.