Based on the balanced panel data of 213 Chinese cities from 2003 to 2016, this paper takes the second batch of low-carbon pilot cities as the research object and uses the difference-in-differences model to analyze and study the impact of low-carbon pilot policies on environmental pollution. The study found that compared with non-low-carbon pilot cities, marked achievements were scored in the low carbon pilot cities of environmental pollution control, but low carbon policy effect present regional heterogeneity in the pilot cities, namely, the policy effects on sub-samples that have smaller population size, higher economic development, more R&D investment of the government, more active financial markets is more significant. Further mechanism analysis shows that the effect of low-carbon policy can be realized through industrial structure upgrading and technological innovation. This study provides policy inspiration and empirical support for further expanding the scope of low-carbon pilot cities.