Abstract: The carbon emission right trading policy is an important measure for achieving the transformation of the low-carbon economy in China. This paper takes panel data of 30 provinces in China from 2007 to 2016 as research object. The difference-in-differences model is applied to explore the effectiveness of the carbon emission right trading policy, and the mechanism of the policy is analyzed from the perspective of inter-provincial differences in the construction land carbon emission intensity. The study shows that: (1) The average value of construction land carbon emission intensity in the pilot area and the non-pilot area has same variation trend during the study period, with the carbon emission intensity value of pilot area a general decline and the non-pilot area a slight rise, which shows that the effect of implementing the carbon emission trading policy is more effective than that of mandatory emission reduction policy. (2) The results of the difference-in-differences model confirm that carbon emission trading right policy significantly reduced the construction land carbon emission intensity under the circumstances of controlling other variables. Moreover, the control variables such as the average land GDP, energy intensity, and industrial structure have significant effects on the construction land carbon emission intensity. (3) Through further investigation of the mechanism of carbon emissions trading policy, we found that the carbon emission right trading policy will ultimately serve to curb construction land carbon emission intensity with a relative decline of energy intensity.