Under the pressure of emission-reduction, China's regional economy needs to eliminate the mode of high energy consumption, high pollution, and high emission. However, the economic development of each region has its own characteristics. Therefore, to analyze the differences in the effect of regional economic development on CO2 emissions, this work made an investigation from the perspective of regional economic competitiveness. First, using the panel data of thirteen economic factors from 2003-2017, this work evaluated the economic competitiveness of 30 provinces from the four aspects: competitiveness of residents’ wealth (WC), competitiveness of opening-up (OC), competitiveness of technology (TC), and competitiveness of industrial structure (IC). Furthermore, the panel principal component regression model (PPCR) was established for the eastern region, the central region, and the western region according to the score of competitiveness in four aspects. The results suggested that the promoting effect of WC on CO2 emissions presented the rule opposite to WC. In other words, the stronger the competitive advantage of WC, the weaker its effect on promoting CO2 emissions. The "pollution refuge" hypothesis was verified in all three regions of China. And the promotion of CO2 emissions by OC was the strongest in the central region, followed by the eastern region, and the weakest in the western region. TC promoted CO2 emissions in the central region, but inhibited CO2 emissions in the eastern and western regions. Finally, the inhibiting effect of IC on CO2 emissions showed the same law as IC. Based on the conclusions, some recommendations were put forward.