Based on the panel data from 2004 to 2018, this paper evaluates the effect of carbon emission trading policies launched in 2014 on the development of green economy in pilot areas by using synthetic control methods, and further studies the mechanism of the policies affecting green economy by using the mediating effects test. The results show that carbon emission trading has a significant effect on the green economy, which is affected by the economic base and location conditions. Technological innovation and the use of clean energy are the main mechanisms by which to promote green economy. Finally, some corresponding policy recommendations are put forward.