The goal of this clinical trial is to evaluate the safety and technical feasibility of a novel brain-machine interface (BCI)-assisted spinal cord stimulation (SCS) and exoskeleton (EXS) system in patients with spinal cord injury (SCI). The primary aim is to determine whether the BCI-SCS-EXS system can safely and effectively improve lower limb motor function and quality of life in individuals with chronic SCI. Participant Population: Adults aged 14-65 years (sex/gender not limited). Patients with chronic SCI (≥6 months post-injury) classified as ASIA A, B, or C. Individuals with stable health status, MMSE ≥22, and secondary education or above. Primary Questions: 1. Is the BCI-SCS-EXS system safe and technically feasible for SCI rehabilitation? 2. Does the system improve lower limb motor function and quality of life in SCI patients? Interventions: Participants will undergo the following procedures: Phase I (Implantation): BCI implantation: ECoG electrodes placed over the motor cortex to decode lower limb movement intent. SCS electrode implantation: 5-6-5 paddle electrodes at T11-L2 for targeted spinal cord stimulation. Phase II (System Calibration): BCI-SCS synchronization: Calibration of decoded motor intent to trigger SCS parameters. SCS-EXO synchronization: Integration of SCS pulses with exoskeleton-assisted gait training. Phase III (Rehabilitation): Daily BCI-SCS-EXS training sessions (60 minutes, 5 times/week for 1 year). Adaptive adjustments to stimulation parameters and exoskeleton support based on performance. Remote monitoring of device performance and emergency intervention for technical issues. Outcome Measures: Primary: Safety (adverse events, device performance, synchronization metrics). Secondary: Efficacy (motor function, neurophysiological function, quality of life). Ethics and Safety: Informed consent will be obtained from all participants. Adverse events will be monitored and reported according to CTCAE 5.0 guidelines. Participant confidentiality will be strictly maintained. This study will provide foundational evidence for the safety and feasibility of the BCI-SCS-EXO system, paving the way for future randomized controlled trials in SCI rehabilitation.