The concept of generative design in Architecture and Urbanism can be found in the 60's before the wide availability of computer technology. This paper decodes one of the urban projects by Metabolist in 1960, which was intended to be a generative system applicable to other sites and evolves over time. Through our analysis, we de-code the formulation process, and verified our hypothesis by re-coding into the program using the software, Rhinoceros and Grasshopper. We found that the determinate factors rule more at the macro level of the project, but the parameters are set by taking the local conditions into account. At the micro level, the system leaves more freedom to accommodate various needs, reflecting the philosophy of the Metabolists. The investigation on this historical predecessor can provide useful insights for parameter settings in future generative system design.