Abstract: Objective In evaluating the service life extension of urban rail transit trains, economic calculation serves as a key basis for decision-making and plays a critical role in determining whether to carry out life extension and associated upgrade. Therefore, it is essential to study the economic viability in urban rail transit train life extension based on whole life-cycle cost. Method Through calculating the whole life-cycle cost for urban rail transit trains, an economic evaluation method for train service life extension is proposed. Urban rail transit train life cycle is divided into four stages: procurement, operation, maintenance, and recycling/disposal. The costs for each stage are calculated separately, incorporating inflation factors and special expenses such as mid-term overhauls, which enables targeted evaluation for factors like interest rate, inflation, and refurbishment costs under service life extension scenarios. An empirical analysis and parameter study are conducted using a typical case, and multi-dimensional calculation is carried out for two scenarios: retirement at the standard 30-year service life and at the extended 45-year service life. Result ＆ Conclusion When excluding the factors such as interest rates, inflation, and residual value at disposal, upgrade and procurement costs are the decisive factors influencing the economic feasibility of service life extension. The higher the procurement cost and the lower the cost, the greater the economic advantage of extending service life. Though interest rate factors significantly affect the overall life-cycle cost of the train, their impact on the economic viability of train delayed upgrade is relatively minor. Inflation factors have a substantial effect on the economics of train life extension; as the inflation rate increases, the cost advantage of life extension diminishes rapidly. When the inflation rate reaches 1.5%, extending train service through upgrade will eliminate any economic advantages.