Abstract: Taking national control and key monitoring firms of wastewaterfrom the Beijing-Tianjin-Hebei, Yangtze River Delta and Pearl River Delta regions in 2015 as research object, and using official turnover as a "quasi-natural experiment", the impact of policy uncertainty on innovation of heavy polluting firmswas examinedfrom theoretical and empirical levels. The results indicate that policy uncertainty will significantly reduce innovation in heavily polluting companies. The conclusions remain robust after considering factors such as the endogeneity of policy uncertainty, intragroup correlation, and the potential impact of turnover frequency. From the two dimensions of enterprise and city, further research shows that state-owned enterprises have a positive adjustment effect on the causal relationship between policy uncertainty and firm innovation, indicating that state-owned enterprises have a stronger ability to resist the risk of policy uncertainty. In addition, the higher the level of urban industrialization development, the more negative and significant impact of policy uncertaintyon firm innovation, indicating that policy uncertainty is not conducive to firm innovationinregions with higher levels of industrialization.