Urban expansion contributes to economic and social development, yet it also presents a range of ecological and environmental challenges. For example, urban expansion leads to the reduction of green spaces and ecological degradation, further contributing to significant increase in greenhouse gas emissions. To address these issues, the Ministry of Housing and Urban-Rural Development in China has implemented the strategy of Ecological Restoration and Urban Repair (ERUR) since 2015. The strategy has introduced three groups of pilot cities and aims to leverage the carbon sequestration potential of forests, grasslands, wetlands, and soil by restoring and rebuilding disrupted urban ecosystems. It not only further reduces urban carbon emissions but also contributes substantially to climate change mitigation. This study considers the ERUR policy as an external shock and employs the Staggered Difference in Difference model (Staggered DID) to empirically evaluate its impact on urban carbon emissions. The results show that the policy has effectively reduced urban carbon emission by 5.6%. The mechanism analysis suggests that the policy primarily lowers urban carbon emissions by increasing urban green areas, thus achieving carbon reduction and sequestration. For every additional thousand hectares of green space, urban carbon emissions reduce by 1.5%. Moreover, the heterogeneity analysis indicates that the ERUR policy may increase the disparity in carbon emissions between cities with the highest and lowest emissions; The ecological foundation, financial basis, and the intensity of policy implementation can affect the effectiveness of the ERUR policy; In the developed eastern regions, the effect is stronger. This study contributes to existing knowledge in several ways: Firstly, contrasting with the predominantly qualitative focus of previous research, the study assesses the carbon emission reduction effect of ERUR policy quantitatively, thus offering a more specific and measurable evaluation of the policy's effects. Secondly, the study highlights the underlying mechanisms of urban ecological restoration policies, which is relatively underexplored in current research. Thirdly, the study uses a Changes-in-Changes model (CIC) to explore the policy's distributional impact on carbon reduction, shedding light on how policies may affect different cities and revealing potential inequalities brought by the climate policies.This study provides the following policy implications: Firstly, it's crucial to extend support to ongoing projects in ecologically vulnerable areas. During this process, the eastern regions could set a precedent, leading the way towards a nationwide embrace of low-carbon and sustainable urban transformation. Secondly, the planning of the ERUR policy could be intricately woven with the concept of low-carbon transformation. This involves strategically developing a portfolio of projects that align with the "Dual Carbon" goals, thereby enhancing the effectiveness of the ERUR policy. Thirdly, regional collaboration is necessary to offset carbon emissions linkage resulting from industrial transfers across regions. This means increasing support for ecological restoration through funding, technology, and skilled personnel, which further benefits the climate justice.