The ongoing Yongsan Park development project began in 1988 with the development of a utilization plan for the US Army base in Yongsan after the Army relocation. This study aimed to draw implications for the Yongsan Park project by focusing on Yongsan Family Park. Among the public records of Yongsan Park and Yongsan Family Park transferred to the Seoul Metropolitan Archives, 53 major records were analyzed. The results are as follows. First, Yongsan Family Park, built on the site of the US Army golf course in 1992, was considered a part of the Yongsan Park plan and holds status as the first phase of the Yongsan Park project. Second, despite its status, Yongsan Family Park opened as a temporary park occupied by urban facilities. A design and detailed roadmap of the development process is necessary to make Yongsan Park more resilient. Third, organizing and systematizing public records is necessary because lessons learned through past park development processes can be applied to the current project. This study is meaningful since it uncovered important issues of urban planning discussed in the process of Yongsan Family Park development through a complete analysis of public records, examined the linkage between Yongsan Family Park, which was not known until now, and the ongoing Yongsan Park project, and reaffirmed the importance of park archiving for long-term development projects.