The purpose of this study is to highlight the idea that the approach and methodology in Landscape Architecture and Urban Studies are rooted in regional planning, and to trace the legacy that can be borrowed from modern city and landscape planning. This study examines the academic relationship between Geddes’ Urban Evolution and McHarg’s Ecological Landscape Planning theory, and explores the significance of regional planning that can be accommodated in both Landscape Architecture and Urban Studies areas at present. As a result, the Geddes’ theory and the McHarg’s ecological landscape planning emphasized a scientific understanding of plans based on evolutionary theories and local research in regional planning. However, the McHarg’s theory was definitely different from the Geddes’ theory and offered its own unique identity and possibilities. First, it was completely focused on the environment. Second, it suggested a concrete methodology consisting of a technique of land suitability analysis to visualize an environmental or regional investigation. Third, McHarg advocated drawings as a visualization tool. McHarg’s theory of ecological landscape planning can be thought of as an evolutionary version of the theory of urban evolution. The study was limited to an applicable range to solidify the possibility of applying the theory in real situation, and more concrete and substantial approaches were suggested accordingly.