As the complexity and diversity of modern urban development increases, the importance of external space planning in urban development projects is growing. This study analyzes the importance and characteristics of each major to enhance the utility value of external space, which aims to improve the efficiency of external space planning and ultimately improve the quality of life of residents. To this end, we reviewed relevant literature, legal guidelines, checklists, and guidelines, and derived 17 external space indicators through expert surveys and FGIs, and organized them into five major categories: accessibility, connectivity, suitability, stability and locality, and landscape planning through FGIs with experts in architecture, urbanism, and landscape architecture. As a result of the analysis, urban planning and design majors prioritized planning that considers the hierarchy and characteristics of the landscape structure, securing public space through the connection of open spaces and pedestrian paths, and connecting organic and three-dimensional buildings, streets, and parks; architectural planning and design majors prioritized harmony with the surrounding environment, securing public space through the connection of open spaces and pedestrian paths, and connecting organic and three-dimensional buildings, streets, and parks; and landscape (environmental) and landscape majors prioritized harmony with the surrounding environment, connecting with adjacent buildings, streets, parks, and green spaces, and planning with integrated landholdings. This emphasizes that urban development projects should secure publicness and integration through harmonious connections with adjacent buildings, streets, parks, and green spaces. This study developed evaluation indicators for evaluating the external space planning of urban development projects and quantified them through the hierarchical analysis method (AHP), which will be useful for future policy formulation and practical application in the fields of urban planning and design, architectural planning and design, landscape (environment), and landscape architecture.