The railway is an important geospatial element as well as an indispensable feature of a nation's infrastructure. It is a material element of a nation's transport network, and it also has social, national defense, military, and even political attributes. Therefore, it has a profound impact on the geographical system, which intensifies the spatial differentiation and reconstruction of the terrestrial system. This paper defines the conceptual connotation and basic characteristics of the railway ecosystem, and analyses the railway network structure, including its gauge structure and national distribution. Secondly, taking Eurasia as the research area, we explore the geographical differentiation of the Eurasian railway network, including gauge differences, the rail system, and the organization of the transport system. Thirdly, this paper investigates the dynamic mechanisms leading to the formation of the Eurasian railway geo-system, with a particular focus on technology dissemination, path dependence, geopolitics, and national defense. Finally, a geographic model of the track gauges of railways in Eurasia is developed. It is found that a complex pattern of railway gauge differences has been formed in Eurasia. Among the numerous railway regulations, three main types of gauge are identified, including 1520 mm, 1435 mm, and 1067 mm. Considerable variation in the coverage of different track gauges is apparent, which provides a physical and technological basis for railway system differentiation and network fragmentation. We find that eight geo-systems in continents of Europe and Asia are strengthened, which divide the Eurasian continent into discrete regions. These differences that geo-systems extend across different numbers of countries, have led to the formation of distinct geopolitical relationships, with five separate track gauge expansion modes, and a geographical confrontation between the 1435 space and 1520 space track gauge areas.