The resource-based city is a type of city with pronounced ageing problems. Correctly grasping the socio-economic adaptability to ageing in resource-based cities can help actively guide the direction of urban development and build a new socio-economic order for the elderly. This paper first selects 125 resource-based cities in China from 2000 to 2020 for characteristic analysis, and finds that resource-based cities are characterized by fast growth rate and a large proportion of ageing population, deep ageing, large regional differences and uncoordinated ageing development with regional socio-economic development levels. The research objective of this article is to explore the temporal evolution characteristics, spatial patterns, agglomeration characteristics, and factors hindering the socio-economic adaptability to ageing in resource-based cities in China from 2000 to 2020. Therefore, an indicator system for assessing the socio-economic adaptability to ageing was constructed, and the improved entropy-weighted TOPSIS model was used to measure the socio-economic adaptability to ageing in 113 resource-based cities in China from 2000 to 2020. The spatio-temporal variation characteristics of the socio-economic adaptability to ageing in resource-based cities were analyzed by descriptive analysis and Moran’s index, and the main obstacle dimensions and obstacle indicators were clarified by the obstacle factor model. The findings can be summarized as follows: Temporal Analysis: Over the timeframe assessed, the socio-economic adaptability of ageing in resource cities demonstrates a consistent year-on-year improvement. The spatial clustering pattern exhibits a noteworthy trend of “significant-significant-insignificant”. Spatial Pattern: Examining the spatial arrangement from 2000 to 2020, areas with medium-low and low adaptability are prominently concentrated in Eastern China and Northeastern China, while regions with medium-high and high adaptability are focal in Northern China and Eastern China. Hebei Province and its neighboring provinces consistently display H-H clustering, contrasting with the Southwestern regions that persistently exhibit L-L clustering. Obstacle Degree Analysis: Across the 2000 to 2020 period, dimensions related to economic development, social participation, and social security consistently emerge as the primary obstacles. Notably, the top 12 average annual obstacle indicators are selected, and within economic development dimension all 4 indicators predominate as the key obstacles. Within the social participation dimension, tertiary sector value added and total retail sales of consumer goods per capita feature as primary obstacles. Regarding social security, impediments are primarily associated with the ratio of Medicare coverage, the ratio of pension coverage, alongside the development level of the social security sector. In the domain of service provision, key obstacle indicators include park area per capita, number of books in public libraries per 100 inhabitants, and public trams and buses per 10,000 inhabitants.