Abstract: As a Nature-based Solution (NbS), the construction and protection of urban green spaces has a positive effect on the mitigation of climate change and the achievement of carbon peaking and carbon neutrality goals. Comprehensively understanding the carbon sink function of urban green space from a multi-scale perspective and analyzing the realization approach and mechanism can help to improve the carbon sequestration capacity of urban green space throughout the life cycle and achieve carbon peaking and carbon neutrality goals. Taking the three scales of urban green space patch, urban green space system, and urban ecological space as the entry points, this research analyzes the approach and mechanism of carbon sink function, and summarizes key approaches to improve the green space carbon sink effect at each scale. In the future, it is necessary to implement research on the evaluation framework of the carbon sink function of urban green space throughout the life cycle, to study the trade-off and synergistic between the carbon sink and other functions of urban green space, and to explore the driving mechanism for the landscape pattern of the carbon sink function of urban green space.