There are abundant tourist resources in mainland Penghu. But how to improve transportation network linking tourist spots become the major issues of the island. The purpose of this research is to study historical transformation of Magong City and to analyze existing as well as future spatial configuration of mainland Penghu. Methodology of this study was Space Syntax, which provided both visual and quantitative digital analytic techniques. The historical transformation analysis was based on the maps, urban planning maps, and relevant studies. The future prediction was first to analyze existing global map of mainland Penghu. Then the axial line of proposed bridge was put into the existing map. The findings indicated that Space Syntax not only represented the five phases of transformations for the core areas of the city, but also pointed out the existing remote conditions and the local spatial pattern which connected transport artillery by a major street of mainland Penghu. In addition, after the proposed bridge complete, the present core areas of the island will expand into Magong City and its harbor, which is the critical transportation node of the island. The remote conditions of the west coast will also be improved by the new bridge project. Therefore, the future design projects in Penghu can follow the results of this study to create suitable living environment for both local people and tourists.