Abstract: Under the "Dual-Carbon" goals, enhancing urban carbon productivity is a key consid-eration in the government's formulation of green fiscal policies aimed at promoting urban low-carbon development. This paper takes the pilot energy conservation and emission reduction financial policy carried out by the two ministries and commissions as a quasi-natural experiment, and uses a multi-period DID model and the Tapio decoupling index model to study the impact of green fiscal policy on urban low-carbon development. The research results show that the imple-mentation of the green fiscal policy has effectively improved the city's carbon productivity and promoted low-carbon urban development. Mechanism analysis shows that the implementation of the green fiscal policy can improve urban carbon productivity by optimising the urban industrial structure and the allocation of production factors, improving the urban innovation environment, and enhancing the urban scientific and technological innovation capabilities. Heterogeneity analysis shows that the policy effect is more significant in cities that are non-resource-based, non-industrial, disclose environmental information, and have local governments that are highly environmentally conscious. The extended research finds that, during the policy implementation period, the economic growth rate in other pilot cities, excluding Tieling and Tongchuan, outpaced the growth rate of carbon emissions, demonstrating a clear trend of improved carbon productivity. Green fiscal policy plays an important role in promoting carbon reduction, growth, and carbon productivity of cities. Urban low-carbon development should focus on green finance by formulating policies to achieve the dual goals of economic development and carbon emissions reduction and related pollution control.