Abstract: With the advancement of urbanization, the scope of urban built-up areas continues to expand, and many problems have emerged in this process. In order to better understand the law of urban development, DMSP/OLS data in five periods of 1992, 1997, 2002, 2007 and 2012 and NPP-VIIRS night light images as data sources in two periods of 2017 and 2019 are selected as data sources, and the scope of Taiyuan built-up areas is extracted by statistical data comparison method. Through the analysis of the temporal and spatial characteristics of the built-up area of Taiyuan, the law of urban expansion is obtained. The results show that: ① from 1992 to 2019, the area of Taiyuan built-up area increased by 249.73km², expanded by 2.6 times, and the growth of built-up area was mainly concentrated in the southeast of Taiyuan.② 2002-2012 and 2017-2019 belonged to the accelerated expansion mode, and the expansion speed was high. From 1992 to 2019, the shift distance of Taiyuan center of gravity was 5676.42m, the average migration speed was 202.73m/a, and the center of gravity generally shifted to the southeast. ③ The driving force of Taiyuan urban expansion mainly comes from the influence of economic development factors, population factors, transportation factors and policy planning factors. The research results provid theoretical basis and data support for Taiyuan urban planning and spatial structure adjustment.

Key words: night lighting image, extraction of built-up area, urban expansion, feature analysis