Based on the data of 36 municipal panels in the three provinces of Northeast China from 2005 to 2016, the spatial and temporal patterns of environmental regulation and carbon emission are analyzed qualitatively. And we use a mediation effects to analyze the influences of environmental regulation on carbon emissions quantitatively. The results show that: (1) The comparison of cities shows that there are obvious urban differences between different cities in the intensity of environmental regulation. The carbon emissions increased first and then reduced; (2) As for the spatial pattern, the intensity of environmental regulation shows a trend of increasing from north to south, and the differences between regions increased gradually. The high-level types of environmental regulation are centrally distributed, and most in cities. The low-level types of environmental regulation are found in the northern part of Heilongjiang Province, and the number of the low-level types is the smallest in cities. The high-level types of carbon emissions are concentrated in regions which are rich in oil and metal resources, such as Liaodong Peninsula and the cities of Daqing and Jilin. And the number of low-level cities has increased, mainly in the northeastern part of the region; (3) The strict environmental regulation in the three provinces of Northeast China not only directly restrains carbon emissions, but also indirectly restrains carbon emissions by optimizing industrial structure and reducing rough investment. Meanwhile, the competition between local governments would reduce carbon emissions of the environmental regulation.