An extensive examination of urban energy system optimization in rapidly urbanizing countries An extensive examination of urban energy system optimization in rapidly urbanizing countries like China fills a research gap. This paper addresses a research need by creating a comprehensive model of urban energy subsystem interdependencies and dynamics. Research simulates and optimizes energy systems using software such as EnergyPLAN, HOMER, and TRNSYS. Sustainable urban energy systems optimize energy transmission nodes, model multi-zone energy systems, and integrate regional models. Urban energy systems are modelled using national energy statistics, literature surveys, and 10-year-old simulation models. Joint power grid-heating network simulations, energy transmission node optimization, and heating network integration with energy storage and conversion nodes are included. The findings illuminate urban energy dynamics, including how energy infrastructure impacts system efficiency, renewable energy integration, and demand-side management. Optimization improves energy efficiency, system resilience, and profitability. Moreover, this study theoretically understands complicated urban energy system dynamics to promote sustainable urban development and energy transition debates. The findings can help policymakers, urban planners, and energy stakeholders optimize urban energy systems and promote sustainable development. The study's theoretical implications go beyond Chinese urban energy efficiency to sustainable urban development and energy transition. Practical implications indicate that integrated energy planning and management informs urban policy and decision-making worldwide.