Understanding of the impact on the thermal effect by urbanization is of great significance for urban thermal regulation, it is essential to determine the relationship between the urban heat island (UHI) effect and the complexities of urban function and landscape structure. For this purpose, we conducted a case research in the metropolitan region of Beijing, China, and >5000 urban blocks assigned with different urban function zones (UFZs) were identified as the basic spatial analysis units. Seasonal land surface temperature (LST) retrieved from remote sensing data were used to represent the UHI characteristics of the study area, and surface biophysical parameters, building forms, and landscape pattern metrics were selected as the urban landscape factors. Then, the effects of urban function and landscape structure on the UHI effect were examined by spatial regression models. The results indicated that: (1) Significant spatio-temporal heterogeneity of LST were found in the study area, and there was obvious temperature gradient with “working-living-resting” UFZs; (2) All the types of urban landscape factors showed significant contribution to seasonal LST, and sorted by surface biophysical factors > building forms > landscape factors. However, their contributions varied in different seasons; (3) The major contribute factors showed a certain difference due to the variation of urban function and landscape complexity. This study expands understanding on the complex relationship among urban landscape, function, and thermal environment, which could benefit urban landscape planning for UHI alleviation.