This is a prospective, open-label, multi-center, single-arm study to evaluate the efficacy and safety of an implantable wireless brain-machine interface (BMI) system in patients with spinal cord injury. Eligible participants will undergo screening after signing informed consent, followed by BMI system implantation. Follow-up visits will be conducted postoperatively to assess brain-control performance and safety.

Inclusion Criteria:

1. Aged 18 to 65 years old (inclusive), with no restriction on gender.
2. Meeting all the following requirements:

(1) Suffering from complete or incomplete tetraplegia secondary to cervical spinal cord injury (C2-C6); (2) Diagnosed in line with the 2019 revised International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) issued by the American Spinal Injury Association (ASIA), with neurological injury grade classified as Grade A to Grade C; (3) Having fulfilled the above diagnostic criteria for no less than 12 months; 3. Confirmed by imaging examinations and neurological evaluations that the motor-related cerebral cortex is structurally intact, functionally normal and free of obvious atrophy, organic lesions or functional disorders; 4. Fertile participants must agree to use effective contraception throughout the trial period; 5. Participants, either independently or with caregiver assistance, are willing to follow investigators' guidance, comply with all procedures stipulated in the study protocol and complete all scheduled trial visits as required; 6. Having normal cognitive function with a Mini-Mental State Examination (MMSE) score ≥20 points (excluding three-step commands, writing and drawing items); 7. Elbow flexor muscle strength ≤ Grade 3 assessed by ISNCSCI scale; 8. Being of good compliance, voluntarily participating in the clinical trial and signing the informed consent form.

Exclusion Criteria:

1. Having received implantation of any metallic objects or devices in the body (e.g., pacemaker, defibrillator, neurostimulator, cochlear implant, electronic devices, drug infusion pumps, etc.), excluding dental metallic implants or other implants confirmed to have no impact on the study.
2. Long-term use of anticoagulants or antiplatelet drugs prior to screening, with antiplatelet drugs not discontinued for at least 2 weeks before surgery; or suffering from hematological diseases such as aplastic anemia and systemic lupus erythematosus; or having clinically significant abnormal coagulation function during the screening period.
3. Having contraindications to magnetic resonance imaging (MRI) or being unable to complete MRI examinations for other reasons.
4. Being assessed by anesthesiologists as intolerant to anesthetic surgery.
5. Having neurological diseases (e.g., cerebrovascular lesions, intracranial infection, neurodegenerative diseases, epilepsy) or a history of craniocerebral trauma leading to severe brain dysfunction or obvious abnormal electroencephalographic signals, as judged by investigators.
6. Suffering from physical or pathological conditions that may cause failed normal healing of scalp wounds.
7. Being in the stage of acute infection or suffering from other severe infections.
8. Having any unstable or severe medical conditions that may interfere with study procedures or confound the evaluation of study endpoints, including previously diagnosed mania, depression, Alzheimer's disease, mood disorders, intellectual disability, other cognitive disorders, severe attention deficit, etc.
9. Suffering from severe dysfunction of vital organs including heart, lung, liver and kidney: such as severe cardiovascular diseases (e.g., hospitalization or cardiac surgery due to myocardial infarction within 3 months, congestive heart failure, myocardial infarction, severe unstable arrhythmia, hypertrophic cardiomyopathy, severe aortic stenosis, aneurysm); severe pulmonary diseases (moderate to severe pneumonia, respiratory failure, etc.).
10. Diagnosed with malignant tumors, autoimmune diseases, peripheral neuropathy, poorly controlled diabetes mellitus, or other severe diseases deemed unsuitable for this clinical trial by investigators.
11. Severe spasticity, severe neuralgia, or uncontrolled complex regional pain syndrome that hinders participants from completing training sessions.
12. Spinal cord dysfunction or injury caused by autoimmune disorders.
13. Having visual impairment that makes it difficult to view display screens for a long time even with standard corrective lenses.
14. Suffering from infectious diseases such as active pulmonary tuberculosis, viral hepatitis (hepatitis B, hepatitis C), syphilis and AIDS.
15. Receiving pharmacotherapy or physical therapy affecting the central nervous system before enrollment, and unable to discontinue such treatments after enrollment as assessed by investigators.
16. Having a history of drug abuse, nicotine dependence or alcohol dependence.
17. Pregnant or lactating females, or those planning to become pregnant during the study period.
18. Having participated or currently participating in any drug clinical trial within 90 days prior to enrollment, or any other medical device clinical trial within 30 days prior to enrollment.
19. Any other conditions deemed inappropriate for participation in this clinical trial by investigators.