The integration of railway facilities and use of new energies is an important way to achieve the carbon peaking and carbon neutrality goals of transportation domain. After analyzing the demand for the integrated development of railway and new energies, this study summarizes the natural conditions of various new energy sources along railways, including solar, wind, geothermal, acoustic, braking, and vibrational energies. The current integration forms, technical characteristics, and equipment levels are then reviewed. The specific integration scenarios between the railway service facilities, carriers, infrastructures, and new energy sources are summarized by category, and the developmental scales and problems of major scenarios, such as photovoltaic systems at the top of railway stations, new-energy locomotives, and self-power supply monitoring equipment, are discussed. Based on the classification of potentials to supply new energies for railways, a series of new integration scenarios and methods are introduced considering the new energy systems of different scales (e.g., micro, small- and medium-sized, as well as large and super-large). A new major scenario that integrates electric equipment for railway infrastructure defects control and small- and medium-sized distributed off-grid photovoltaic systems is proposed. Furthermore, the future trends, core technologies, and key developmental directions for the integration of railway and new energies are proposed from the aspects such as energy capture and conversion, load, energy storage, and energy management. The results can provide references for planning, construction, and transformation development research in related fields.