To address the problems of renewable energy accommodation and supply–demand imbalance caused by the dynamic evolution of load demand over the life cycle of western mining areas, a life-cycle dynamic configuration method for the energy system of underground coal mines is investigated. Based on the production organization in the construction, early-stage mining, mid-stage mining and late-stage mining periods, a multi-energy coupling framework for electricity–heat–cooling is constructed to reflect the differences between above-ground and underground loads. A multi-stage mixed-integer linear programming model is developed, which integrates photovoltaic (PV) generation, electrical energy storage, chillers and external power/heat supply. The objective is to minimize the total life-cycle cost consisting of investment, operation and maintenance, purchased energy and carbon emission costs by optimally sizing PV, energy storage and primary network equipment, and by representing the temporal evolution of source–load relationships through typical-day load profiles and year-by-year capacity expansion decisions. A typical western underground mine is used as a case study, and two scenarios are compared: traditional static one-shot configuration and life-cycle dynamic configuration. The results show that the dynamic configuration increases the average installed PV capacity and renewable penetration through staged PV and storage expansion in key years, while restraining the required capacity of primary network equipment and substantially reducing curtailment over the whole life cycle. Compared with the static configuration, the dynamic configuration reduces the total life-cycle cost by about 17.9% and the carbon emission cost by about 50.2%. The proposed life-cycle dynamic configuration method can satisfy secure energy supply for mining areas while balancing economic performance and low-carbon goals, and it provides a technical reference for planning clean energy systems in western mining areas and similar energy-intensive industrial parks.