This is a multicenter, randomized, double-blind, placebo-controlled Phase III clinical trial.

The study plans to enroll 240 adult patients with Alcohol Use Disorder (AUD). After providing written informed consent and undergoing screening for eligibility criteria, eligible subjects will be randomized in a 2:1 ratio to receive treatment in either the experimental group (1.5 g Naltrexone Hydrochloride Implant plus non-specific supportive psychotherapy) or the control group (placebo implant plus non-specific supportive psychotherapy).

On Day 1, subjects will receive a single subcutaneous implantation via a small abdominal incision, receiving either the Naltrexone Hydrochloride Implant or the placebo implant. Following implantation, subjects will be hospitalized for at least 2 hours (the investigator may extend this observation period up to 3 days based on the patient's condition). Subjects will change the wound dressing by themselves on postoperative Day 3.

Efficacy and safety assessments will continue through Week 24 post-randomization/dosing, involving a total of 11 visits. Among these, Visit 5 (Week 3) will be conducted via telephone, while all other visits will be performed as outpatient clinic visits.

Inclusion Criteria:

Diagnosis of moderate to severe Alcohol Use Disorder (AUD) based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria (meeting four or more diagnostic criteria; refer to Appendix 1 for details).

Exclusion Criteria:

Pregnant, breastfeeding, or pregnant with a positive pregnancy test at screening. This includes women of childbearing potential planning to become pregnant during the study.

Note: Women of childbearing potential are defined as those who are biologically capable of becoming pregnant. To be considered not of childbearing potential, a female subject must meet one of the following: 1) Have had a hysterectomy or bilateral oophorectomy; or 2) Be post-menopausal, defined as having no menses for more than 12 consecutive months.

Significant abnormality in liver function (e.g., AST or ALT > 3 times the upper limit of normal), liver failure (e.g., presence of ascites, jaundice, coagulopathy, hepatorenal syndrome, or hepatic encephalopathy), or liver/gallbladder ultrasound findings that may significantly impact the assessment of the investigational drug's efficacy and safety.

History of severe pancreatitis or severe delirium tremens. Presence of any severe/uncontrolled systemic diseases (e.g., respiratory, cardiovascular, gastrointestinal, neurological, hematological, urogenital, or endocrine disorders) or psychiatric disorders (e.g., Major Depressive Disorder, Schizophrenia, Bipolar Disorder) or other major illnesses, which in the Investigator's judgment could interfere with the provision of informed consent, make study participation unsafe, complicate the interpretation of study outcome data, or otherwise affect the achievement of study objectives.

Potential need for hospitalization or surgery during the study period, including scheduled elective surgeries that cannot be postponed.

Diagnosis of a Substance Use Disorder (other than alcohol or tobacco) based on DSM-5 criteria within the past year (prior to randomization/dosing), such as benzodiazepines, amphetamines, opioids, or cocaine.

Use of anti-relapse medication (e.g., Naltrexone) or receipt of systemic psychological support therapy within 30 days prior to randomization/dosing.

Currently receiving treatment for substance use disorders (e.g., opioids, amphetamines, alcohol), or received opioids within 7 days prior to randomization/dosing, or may require opioid treatment during the study; or positive urine drug screen for opioids, cannabis, amphetamines, etc., or positive naloxone challenge test on the day of randomization/dosing.

Suicidal risk based on Investigator's clinical judgment, or history of suicidal or self-mutilating behavior.

Allergy to the investigational product or its excipients (polylactic acid, magnesium stearate) or local anesthetics.

Currently participating in any investigational drug or device study, or has used any investigational drug or device within 30 days prior to randomization/dosing.

Skin infection at the implantation site, systemic skin disease, or keloid scarring that may affect the assessment of the investigational drug's efficacy and safety.

Clinical or laboratory evidence of Human Immunodeficiency Virus (HIV) or Syphilis infection.