In view of the insufficient research on the response law of urban thermal environment and the Impervious Surface Distribution Density (ISDD), this paper selected Beijing as a case study. On the basis of the MODIS data, the average temperature difference between the urban construction and marginal areas was calculated as the UHI intensity (UHII). In combination with the characteristics of the UHII level, six typical regions (ⅠXierqi, Xisanqi, Huilongguan, ⅡDongsi, Xi’anmen, Xinjiekou, Ⅲthe middle of Fengtai District, ⅣSihui, Dingfuzhuang, Dongba, ⅤShijingshan District, Ⅵnear the Sijiqing bridge on the North Fourth Ring Road) with a high expected UHII level were selected to study the response relationship between the UHII level and the ISDD. Finally, Landsat data was used to invert the surface temperature to study the critical point and optimal scale of surface temperature response to the ISDD in urban construction areas and typical regions. Results show that the following. (1) The frequency of occurrence of UHII levels, their variation degree during the day and at night have a certain correlation with the ISDD, and the variation characteristics of the UHII under similar ISDDs are the same. (2) The distribution characteristics of the surface mean temperature in urban construction areas and the ISDD are obviously consistent. As the scale radius r increases, the response is more obvious. Besides, there are critical points for the response of the surface temperature to ISDD. The response of critical points gradually increases with the decrease of scale radius r. When scale radius r=1000 m, the ISDD reaches 60%, and its influence tends to weaken; the critical points of r=500 m and r=300 m are 69% and 83%, respectively. (3) The optimal scales of different typical regions have differences. The optimal scale of Xierqi, Xisanqi, and Huilongguan is 150 m, and that of Dongsi, Di’anmen, Xinjiekou, and Qingqiao near the fourth ring is 60 m. However, seasonal changes have little impact on the optimal scale. The optimal scale can measure the degree of fragmentation of the impervious surface distribution in different regions and the single degree of surface type to some extent. This study can provide a reference for urban planning and UHI governance.

urban heat island effect;impervious surface distribution density;urban construction area;critical point;response law