This is a multicenter, randomized, double blind, placebo-controlled, parallel design study to evaluate the efficacy and safety of Tunodafil Hydrochloride Tablets in men with erectile dysfunction.

Inclusion Criteria:

• - Male subjects aged between 18 and 65 years (inclusive) diagnosed with Erectile Dysfunction (ED).

• At Visit 1, subjects must have an International Index of Erectile Function-5 (IIEF-5) score ≤ 21, with a disease duration of at least 6 months.

• Subjects must have a stable marital relationship or a stable female sexual partner for at least 3 months prior to screening and throughout the study period.

• Subjects must agree to attempt sexual intercourse at least 4 times per visit cycle.

• Subjects agree not to use any other ED treatments during the study, including PDE5 inhibitors, traditional Chinese medicine (including decoctions and patent medicines), or medical devices for ED treatment.

• Subjects (and their partners) must have no plans for conception from the time of screening up to 3 months after the last dose, and must voluntarily use effective contraceptive measures.

• Subjects must voluntarily provide written informed consent.

• Upon completion of the run-in period, subjects must meet all of the following three conditions:

  • At least 4 sexual intercourse attempts were made during the run-in period; ② The failure rate of sexual intercourse attempts was ≥ 50% (failure defined as at least one "No" answer to the first three questions of the Sexual Encounter Profile [SEP] diary); ③ The IIEF-Erectile Function (IIEF-EF) domain score was ≥ 5 and ≤ 25.

Exclusion Criteria:

• - Subjects with obvious congenital malformations or anatomical abnormalities of the genitalia that significantly impair penile erection.

• Subjects with erectile dysfunction caused by other sexual dysfunction disorders (e.g., ejaculatory disorders) or uncontrolled endocrine diseases despite medication (e.g., hypogonadism, hyperthyroidism/hypothyroidism, pituitary tumors).

• Subjects with erectile dysfunction resulting from spinal cord injury or radical prostatectomy.

• Subjects with a history of penile prosthesis implantation.

• Subjects with a history of sudden hearing loss or deafness.

• Subjects who have previously failed PDE5 inhibitor therapy for erectile dysfunction.

• Subjects with any history of the following cardiac conditions:

  • Myocardial infarction or stroke within the past 6 months;
  • Concomitant unstable angina or angina occurring during sexual intercourse;
  • New York Heart Association (NYHA) Class ≥ II heart failure within the past 6 months;
  • Concomitant uncontrolled hypertension (≥160/95 mmHg), hypotension (<90/60 mmHg), or orthostatic hypotension.

• Subjects currently using, or unable to discontinue during the study, any formulation of nitrates or nitric oxide (NO) donors, α1-adrenergic receptor blockers (e.g., doxazosin, prazosin), strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, ritonavir), or guanylate cyclase stimulators (e.g., riociguat).

• Subjects with a history of anti-androgen therapy, or androgen replacement therapy initiated less than 3 months prior to screening without a stable maintenance regimen.

• Subjects with poorly controlled diabetes mellitus, defined as fasting blood glucose >1.5 times the upper limit of normal (ULN), or those with diabetic complications (diabetic nephropathy, peripheral neuropathy).

• Subjects with severe hepatic or renal impairment, defined as AST and/or ALT >2 × ULN; or creatinine clearance (CrCl) <30.0 mL/min.

• Subjects with a history of severe chronic or acute hepatitis.

• Subjects who have used vacuum constriction devices (VCD), intracavernosal injections (ICI), or other ED therapies and are unable to discontinue these treatments during the study.

• Subjects with known color vision abnormalities, retinitis pigmentosa, macular degeneration, non-arteritic anterior ischemic optic neuropathy (NAION), or other fundus disease histories.

• Subjects with severe central nervous system damage within the past 6 months (cerebrovascular diseases such as cerebral hemorrhage or ischemia, inflammatory brain diseases such as encephalitis or meningitis, craniocerebral trauma, or spinal cord injury), or peripheral nervous system injury or lesions.

• Subjects with a history of high-risk arrhythmias, or ECG-confirmed arrhythmias, or those with clinically significant abnormal ECG findings at screening as judged by the Investigator.

• Subjects with a history of malignant tumors within the past 3 years (excluding basal cell carcinoma, squamous cell carcinoma of the skin, or other non-invasive lesions deemed cured by the Investigator with minimal recurrence risk).

• Subjects with a known hypersensitivity to the investigational product or drugs of the same class.

• Subjects with a history of psychiatric disorders.

• Subjects with a history of substance abuse, drug addiction, or alcoholism (characterized by impaired tolerance, withdrawal, or control over drinking behavior) within the past year.

• Subjects who participated in another clinical trial within 1 month prior to screening.

• Subjects whose female partners are <18 years of age, or whose partners are known to be pregnant at screening, unwilling to use appropriate contraception during the study, or are breastfeeding.

• Subjects whose partners have gynecological conditions that may affect sexual activity or other medical conditions limiting their participation in the clinical trial.

• Subjects deemed unsuitable for inclusion by the Investigator for any other reason.