In the process of urbanization, energy consumption has significant effect on carbon emissions. The aim of this paper is to analyze the impact of urbanization on carbon emissions for different income levels across 29 provinces of China during 1995-2015. The improved STIRPAT model provides the theoretical foundation for this research. Then, the threshold analysis was used to assess the effect of urbanization on carbon emissions. On the basis of the average annual income, two threshold points that divide the whole sample into three groups were identified, namely, 1) an average annual income of 7400 RMB and 2) an average annual income of 16,250 RMB. The result shows that effect of urbanization on CO₂ emissions varies in terms of income stages and specific regions. Finally, the policy implication was discussed.