China's rapid urban development over the past few decades has been remarkable, but the early growth-oriented "incremental planning" encouraged the disordered sprawl of China's urban land. The accelerated mobility of population in the wake of globalization and the rapid urbanization of China, which has provided a platform for more movement of people between cities, making urban shrinkage caused by this kind of sprawl a common phenomenon. Resource-based cities, facing unprecedented challenges due to resource depletion, over-exploitation and environmental degradation, are quite vulnerable to this disordered growth. Therefore, monitoring the extent of urban shrinkage, identifying and analyzing the evolution of urban spatial use efficiency will be conducive to proposing reasonable and scientific urban development guidelines, as well as to the transformation of resource-based cities. This paper takes prefecture-level resource-based cities in China as the subject, combining the concepts of urban expansion and urban shrinkage in an urban system. The theoretical analysis of the urban expansion mode and the degree of urban shrinkage is conducted, followed by a discussion of the evolution of urban spatial use efficiency and its causes according to different stages of urban development, and finally, strategies to improve spatial use efficiency are proposed. The main findings of the study are as follows: (1) The overall scale of spatial expansion of resource-based cities in China gradually becomes larger, with looser and more complex spatial forms. (2) The urban shrinkage of resource-based cities in China also shows obvious geographical differences, with the eastern region having a high density of built-up areas but a low degree of overall shrinkage, while the northeastern and western regions have a lower density of built-up areas but a more severe degree of overall shrinkage. (3) The overall spatial use efficiency of resource-based cities in China is not high. In different types of resource-based cities, there are differences in the impact of population, economy and land on urban spatial use efficiency, and it is of great practical significance for cities to monitor and assess these fluctuations.