Environmental regulation, as one of the important driving forces to achieve low-carbon development of tourism, is also an effective way to achieve the goal of "carbon peaking and carbon neutrality" of tourism. Based on the comprehensive index method and bottom-up method, this paper measured the environmental regulation level and tourism carbon emission intensity of 30 provinces in the Chinese mainland from 2005 to 2019, and discussed the impact of environmental regulation on tourism carbon emission intensity and its regional heterogeneity with the help of panel regression model and panel threshold model. The results show that:①During the study period, the carbon emission intensity of China's overall tourism industry showed a downward trend; Among them, the central region has the most obvious downward trend, followed by the western, eastern and northeastern regions. ②The level of environmental regulation in China shows an increasing trend, and its regulation effect is more significant in the area on the right side of Hu Huanyong Line, showing a gradient distribution characteristic of decreasing from east to west. ③ The environmental regulation has obvious "forced emission reduction" effect on the carbon emission intensity of tourism, but there is a certain "green paradox" phenomenon in the Northeast China; There is a single threshold for the impact of environmental regulation on the carbon emission intensity of tourism. When the tourism energy intensity is less than the threshold, there is a significant "forced emission reduction" effect, while when the tourism energy intensity exceeds the threshold, there is a "green paradox" effect. ④The environmental regulation in the eastern region failed to pass the threshold effect test; There is a single threshold value in the central region, and the environmental regulation effectively promotes the decline of carbon emission intensity of tourism, and there is no "green paradox" phenomenon; There are single and double threshold effects in western China and northeast China respectively, and the environmental regulation first promotes and then inhibits the carbon emission intensity of tourism.