Abstract: It is necessary to research the city scale, especially the change of spatial-temporal pattern and the dynamic evolution of which is the key to promote regional coordinated development. Based on the night-time light data, this paper calculated the city scale at county level in China during the 1992-2015 by average night light index, then analyzed it by ESTDA framework. The result shows: First, the core-periphery structure and the local spatial pattern of city scale is stable, but was becoming fluctuating. The city scale was growing slowly, but the city local correction is weak, and lacks the force of common motivation to jump upward. Second, the spatial pattern of city scale was separated by Jing-Shan economic trough belt, 110°E belt, and 100°E belt, however the Hu Line may be broken in the future. Third, the local spatial dynamics, growth volatility and local dependence of the city scale after 2003 was increased, and the local dynamics of city scale becomed stable in east, but unstable in west. Meanwhile the center of growth volatility and local dependence shifted to the south and northeast; Forth, the main factors affecting the spatial-temporal pattern and dynamic evolution of city scale at county level were the natural factors, traffic conditions, urban administrative levels, spatial effects, policy orientation and economic development level, and so on. Finally, this research has proved that it is scientific to use the night-time light data to calculate the city scale, and it is important to establish a network for different regions to achieve coordinated development.