With the advancement of urbanization in China, the rapid expansion of cities has reduced the alternative land use and intensified the conflict between people and land, and the adaptation and optimization of urban spatial patterns have become an important work in current urban research. Based on the comprehensive modified the long-term series DMSP-OLS and NPP-VIIRS nighttime lighting data, the spatial analysis method of GIS and urban expansion indicators are used to reveal the spatial and temporal change process of urban built-up areas in the center of gravity of Guangdong-Hong Kong-Macao Greater Bay Area from 1992 to 2020. The results reveal that the built-up area of the urban agglomerations in the study area generally shows an increasing trend year by year, but there are some periods when the area decreases or remains unchanged, while the expansion rate shows a gradual decrease over a long time scale. The compactness of the urban agglomerations in the GBA decreases over time, and the fractal dimension fluctuates but remains unchanged, while the spatial distribution of the urban agglomerations in the GBA shows a "southwest-northeast" direction during 1992-2020, with the center of gravity moving to the northeast gradually. On the side, the urban expansion shows a fluctuation of "diffusion-coalescence-diffusion". The expansion of urban built-up areas is influenced by both natural and socio-economic factors, and the degree of influence varies in different periods.