Against the background of accelerating global population ageing, accurately assessing ageing has become a crucial prerequisite for formulating policies related to pension systems, healthcare, public finance, and labor markets. For a long time, the old-age dependency ratio based on chronological age has been widely used due to its computational simplicity and data availability. However, it implicitly assumes high homogeneity among older populations in terms of health status, labor participation capacity, and economic dependency, which makes it difficult to capture the substantial cross-country and intertemporal differences in ageing processes and may lead to an overestimation of the actual burden of ageing. With increases in life expectancy, improvements in health conditions, and changes in human capital structures, scholars have gradually developed a series of alternative approaches to redefining and measuring population ageing from multiple dimensions, including remaining life expectancy, economic dependency, health and physical functioning, and education and human capital. This paper systematically reviews the theoretical evolution and methodological transformation of population ageing measurement frameworks. Following a development trajectory from “single-dimensional to multidimensional” and from “static to dynamic”, it classifies and evaluates major measurement approaches based on age, economic dependency, health and physical functioning, education, and multidimensional indicators. A comparative analysis of these approaches reveals that multidimensional and dynamic measures can better capture the heterogeneity of older populations and provide a more accurate assessment of the actual burden of ageing. However, existing measures still face limitations in indicator weighting, cross-national comparability, and the treatment of interactions among population characteristics. Therefore, this paper argues that future research should integrate multidimensional population characteristics while accounting for regional and group-specific differences to construct ageing measurement frameworks with stronger explanatory power and greater policy relevance, thereby providing a more comprehensive and reliable basis for strategies to actively respond to population ageing, developing human resources among the elderly, and achieving high-quality population development.