Motor dysfunction is one of the severe sequelae of spinal cord injury (SCI). As an emerging neuromodulation technique, epidural spinal cord stimulation (eSCS) involves implanting electrodes into the epidural space of the spinal cord to directly stimulate spinal neurons. It can effectively activate the residual function of neural pathways below the injury level, markedly increase the excitability of motor neurons caudal to the lesion, and even enable patients with complete SCI to regain voluntary motor functions such as standing and stepping. This article systematically reviews the fundamental principles, mechanisms of action, and clinical applications of eSCS.