Spinal cord injury (SCI) is a severe neurological disorder caused by traumatic or non-traumatic factors that damage the structure and function of the spinal cord, leading to sensory, motor, and autonomic nervous system dysfunctions. It imposes a heavy burden on patients, their families, and society at large. Epidural electrical stimulation (EES), also known as spinal cord stimulation (SCS), has emerged as a novel neuromodulatory intervention strategy, showing promising clinical potential in promoting neurological function recovery after SCI with preliminary clinical evidence accumulated to date. This review systematically summarizes the potential mechanisms by which EES facilitates neurological recovery post-SCI, focusing on four key aspects: (1) enhancing nerve impulse conduction, including the regulation of neuronal membrane potential and ion channels; (2) optimizing the local microenvironment, such as improving regional blood circulation, alleviating inflammatory responses, and alleviating oxidative stress-induced damage; (3) promoting neural plasticity, involving the synergistic effect of multi-level neural pathways, upregulation of neurotrophic factors, synaptic plasticity, and axonal regeneration; (4) mediating the structural remodeling of ascending and descending neural pathways and spinal intrinsic circuits, thereby providing a structural basis for the manifestation of neuroplasticity. In addition, relevant clinical research evidence is comprehensively outlined herein. This review aims to provide a solid theoretical basis and academic support for deepening the research on the mechanisms of EES and promoting its standardized clinical application.