Overlaying different versions of maps to investigate phenomenal dynamics of development in human society is one of the most frequently used methods in Cartography. Due to changes of geodetic datum for mapping in Taiwan area there caused enormous problems in nearly half of the last century when map users applied overlaying analysis. In this research we calculated scale factor, area factor, and coordinate differences to analyze the effects on overlaying analysis using different geodetic datum of topographic maps. We also proposed relevant methodology and actions to solve the problems.