Abstract: Scientific understanding of the temporal and spatial patterns and driving factors of urban surface thermal fields is an important prerequisite for optimizing urban ecosystems. Kashgar City is the throat hub of civilization and transportation between the East and the West, and its strategic position in the "Belt and Road" is very important. In this paper, the Landsat series of remote sensing images in 1998, 2008, and 2018 of the city of Kashgar on the western edge of the Tarim Basin have been used. The land surface temperature was retrieved with the radiative transfer equation algorithm and to analyze the spatial variation of surface temperature in Kashgar City by using transfer matrix with the help of “GIS” and “RS” technology. Next, on the basis of extracting impervious surface index and vegetation coverage, 6 types of influencing factors including altitude, slope, population density, IBI, FVC and land use type are integrated to detect the spatial heterogeneity and driving factors of the surface thermal field with geographic detectors in Kashgar City in the past 20 years.The results showed as follows: First, the middle temperature area and the higher temperature area are contiguously distributed in the urban built-up area, the low temperature and the lower temperature area are inlaid in the periphery of the built area in dots, and the high temperature and extremely high temperature areas are distributed in patches in the north of the urban area. Second, with the continuous development of the region, the medium temperature zone gradually dominates. In 2018, the temperature zone area was 161.89 km2, meanwhile, duing to the coexistence of the phenomenon of "invading cultivated land and expanding towns" and "forestation", the low temperature zone increased by 4.58 %, the bare land is effectively improved, and the area of the high temperature and ultra-high temperature zone is reduced by 20.41km2. Last, the spatial differentiation of the surface thermal environment in Kashgar is the result of multiple factors. The core factor affecting the spatial differentiation of LST is IBI. The three-year contribution rates are 87.8%, 74.6%, and 80.8%, and the multi-factor interaction is obvious. The interactive explanatory powers of IBI and land use types in 1998, 2008 and 2018 were 0.912, 0.746, and 0.873, respectively. The research results can provide reference for urban ecological protection and regional sustainable development in Kashgar City.

Key words: land surface temperature, geographical detector, conversion matrix, Kashgar city