China’s railway infrastructure construction is developing from “construction-oriented” to “construction and management balanced.” Traditional operation and maintenance methods have many drawbacks, and there is an urgent need to establish an innovative intelligent operation and maintenance system. Digital Twin (DT), a technology of interacting between the real physical system and virtual counterpart, overcomes the limitations of traditional simulations and test conditions, and can offer the accurate assessment for actual operating condition at the fastest speed and optimal cost. digital twin can interact with Internet of Things, Building Information Modelling, Structural Health Monitoring, numerical simulation and artificial intelligence through the integration of real physical system and the associated virtual model in order to realize the real-time monitoring, simulation, prediction, diagnosis and decision-making of the system. This paper reviews critically the research progress, basic principles and technical methods of digital twin, and discusses the applications of Digital Twin integrating with Building Information Modelling, structural health monitoring, artificial intelligence, New Information Technology, etc. Then, the research advances of the applications of digital twin in railway operation and maintenance are summarized, including intelligent inspection (monitoring) testing, digital twin virtual modeling, performance degradation modeling, and optimized maintenance strategy determination. Finally, this paper presents the framework for intelligent operation and maintenance of railway infrastructure by using digital twin technology，and discusses the main problems and solutions of its applications in railway maintenance. From the critical review, the digital twin technology can provide a methodology for intelligent railway operation and maintenance management.