Abstract: Ensuring easy and equitable access to open space by all residents is a significant aspect of assessment of urban environmental sustainability. However, the current evaluation of open space often takes the per capita green area as the core indicator, ignoring its actual distribution and use, and rarely considering the users’ actual walking routes or their perception of the pedestrian network. Citing Hong Kong’s open space as a case, this research applies the 3D spatial design network analysis (3D sDNA) technology in the GIS platform to evaluate pedestrian accessibility based on generic human route choice preferences. By combining social characteristic variables such as residential density, elderly population proportion, and income level, it identifies the areas with insufficient open space but high population density or more socially vulnerable groups. This approach provides a refined quantitative method for assessing the accessibility of open spaces in high-density cities, and helps to assist planning and design practices based on a human-centered equity perspective.