<p>Changes in policy mix (CPM) are dialectically unified with the consistency, coherence, and reliability of policy mix, which should also be the key components of policy mix analysis. This study focused on prevalent CPM in real-world contexts and constructed a conceptual framework for it. Using data from China’s heavily polluting industries, the inducing mechanisms and effects of CPM on green innovation (GI) were examined. Empirical findings revealed that during the observation period, the policy instrument system consisting of environmental and innovation policies showed a dynamic adjustment trend. CPM (both longitudinal and transverse) were effective and significantly promoted GI. Using occasional environmental pollution and destruction accidents as instrumental variables, the causal relationship between CPM and GI was verified. Heterogeneity analysis indicated that GI had a cumulative effect and that GI in heavy industries exhibited spontaneous motivation. Specifically, the influence of CPM on GI became larger with an increase in the industry’s GI level. Compared with light industries, heavy industries with higher migration costs were more inclined to respond to CPM with GI. And mechanism analysis revealed that longitudinal CPM induced GI by creating a favorable market climate and promoting public environmental participation, whereas transverse CPM promoted GI solely through the former. The significance of these findings lies in the valuable insights they offer for understanding policy mixes and informing subsequent empirical studies.</p>