Chinese modernization is the modernization of a huge population. Building a pension finance system with Chinese characteristics is a strategic task to meet the demands of the times and achieve high-quality development of pension finance, as well as a necessary condition for satisfying the people’s growing needs for a better life in old age. Grounded in the new development stage of the “15th Five-Year Plan Period”, this paper adheres to the core philosophy of “investing in people”, and takes promoting high-quality population development to underpin Chinese modernization as its fundamental direction. Based on the “financial function view”, this paper constructs an analytical framework of “products-institutions-markets” for pension finance. This paper proposes that pension finance is an economic and financial system operating under the long-term constraints of population ageing and in the context of big data. It constitutes a unified system encompassing the necessary financial products, financial institutions, and financial markets for implementing the three national strategies: actively responding to population ageing, building up China’s strength in finance, and advancing Digital China. Adhering to the core pathways of tripartite synergy among “products-institutions-markets” and dual-chain integration of the “financial capital chain and real industrial chain”, this paper advocates a function-oriented approach to continuously drive product innovation and service provision, fully leverage the synergistic functions of intermediary and market-based financial institutions, promote the deep integration of pension funds with the capital market, and achieve a shift from “demographic dividend” to “financial dividend”. This paper further explores the internal mechanisms through which “data elements, digital technologies, and digital platforms” propel the transformation of pension finance toward precision, intelligence, and inclusivity. Through field research on the innovative practice of the “Digital Smart Elderly Care City” in Ziyang, Sichuan Province, this paper delves into the pioneering value of the “elderly care-finance-data” trinity model in addressing ageing issues, aiming to provide theoretical support and practical guidance for digitally empowering the high-quality development of pension finance during the “15th Five-Year Plan Period”.