Hydrogen energy has emerged as a crucial element in the global effort to combat climate change and achieve sustainable development goals. China, in alignment with its decarbonization objectives, is actively pursuing diverse hydrogen production methods to reduce carbon emissions and enhance energy efficiency. By the end of 2023, China had a significant annual hydrogen production capacity, with a focus on sources like coal, natural gas, and electrolyzed water. The country aims to scale up its production from renewable sources in the coming years to further reduce reliance on traditional energy sources. Leading Chinese cities, including Beijing and Shanghai, have been designated as hydrogen fuel vehicle demonstration urban agglomerations, demonstrating the practical applications of hydrogen energy in transportation, energy provision, and industrial processes. These cities are playing a pivotal role in driving the adoption of hydrogen technology across various sectors and showcasing the potential for urban sustainability. Moreover, a comprehensive assessment of the life cycle emissions and economic feasibility of different hydrogen production methods is essential for the widespread deployment of hydrogen energy. Studies focusing on gray, blue, and green hydrogen technologies provide valuable insights into emission reduction potential and economic viability, with a particular emphasis on carbon capture and renewable energy tariffs. As China continues to prioritize the development of hydrogen energy, it is crucial to evaluate the emission reduction potential of diverse production methods at the city level. By analyzing the carbon dioxide emissions of various hydrogen production methods in leading cities and considering different technological scenarios, policymakers can make informed decisions to advance hydrogen technology and contribute to a more sustainable future.