<p>The trend of urbanization has challenged the sustainable development of cities. The presence of open spaces is regarded as a key factor in balancing the environmental aspects of future cities. Given that open spaces involve diverse elements and complex, interdependent relationships, conducting open space planning solely on the basis of designer requirements may yield limited effectiveness. Therefore, we established a future city open space assessment model that considered both user needs and design requirements and comprehensively discussed the planning and design of open space in future cities. First, the fuzzy Delphi method was employed to consolidate user needs and determine user consensus. Subsequently, quality function deployment was adopted to explore the influence relationships between user needs and design requirements, and the decision-making trial and evaluation laboratory-based analytic network process was applied to determine the order of priority for design elements following interaction effects. Finally, the proposed model was empirically verified using a case study based in an urban setting in East Asia. The results of the case study indicated that pedestrian space, restrictions on plant height and length, and accessible design should be prioritized in open space planning. The findings of this study can help urban planners to systematically enhance the quality of open spaces and ensure that their planning and design align with the requirements of future city development, thereby realizing urban sustainable development.</p>