Rail transit features high levels of energy consumption and carbon emission; therefore, transforming its energy structure and developing a novel rail transit energy system with self-consistent energy supply become significant approaches for realizing carbon peak and neutrality in China. In this article, we first review the demand for the integrated development of rail transit and energies, summarize the current status and development trends of the integration, and analyze natural endowments for the integration in terms of solar and wind resources. Subsequently, based on the characteristics of electrified and non-electrified rail transits, critical technology paths are proposed considering the natural endowments of renewable energies. Moreover, based on the assessment of self-consistent supply potentials of new energies, a series of scenarios and methods are introduced. A roadmap and suggestions are proposed for rail-energy integration development, aiming to a self-consistent energy system construct for rail transit. The suggestions include: (1) encouraging technology innovation regarding green and intelligent rail transit to form a technology system for rail-energy integration; (2) implementing major scientific and technological projects to coordinate the industrial layout of new energy and rail transit; and (3) formulating support policies to create a policy guarantee system for green finance.