With the increasing complexity and specialization of substation operation and maintenance (Q&M), traditional training methods are insufficient to meet the demands of efficient and comprehensive education. The integration of virtual reality (VR) technology and knowledge graphs (KGs) present new opportunities for innovating O&M training systems. However, existing VR training systems do not fully utilize KGs to provide comprehensive training frameworks, and systems that integrate KGs often lack realism and intuitive scene representation. Moreover, research on applying VR technology and KG to substation O&M training remains relatively scarce. To address these issues, this paper proposes a substation O&M training system based on VR and KGs. The system employs VR technology to construct a highly realistic training environment, offering functions such as equipment operation, fault diagnosis, and emergency response, allowing trainees to engage in hands-on training within an immersive virtual scene. Simultaneously, the system integrates KGs to systematically present the knowledge framework of substations O&M, assisting learners in quickly accessing the required information and enhancing learning efficiency. This system has been applied in three organizations, received positive feedback, and trained numerous O&M personnel, significantly improving training effectiveness and work efficiency, indicating broad application prospects.