This is a phase Ⅲ, multicenter, randomized, evaluator-blinded, parallel-group, active-controlled study to assess the efficacy and safety of ciprofloxacin 0.3% plus fluocinolone acetonide 0.025% otic solution vs ciprofloxacin 0.3% otic solution in the treatment of AOE, and to assess the pharmacokinetic properties in 12 selected adult subjects. Eligible subjects will be randomized at 1:1 ration to either the treatment arm or control arm. All subject will receive 7 consecutive days of either ciprofloxacin 0.3% plus fluocinolone acetonide 0.025% otic solution or ciprofloxacin 0.3% otic solution alone. The main objectives are to assess the efficacy and safety of ciprofloxacin 0.3% plus fluocinolone acetonide 0.025% otic solution in the treatment of AOE, and to assess the plasma concentration of ciprofloxacin and fluocinolone acetonide after multiple doses of test drug in 12 adult subjects, and evaluate the PK parameters.

Inclusion Criteria:

1. Male or female subjects with age of ≥3 years.
2. Subjects with clinical diagnosis of unilateral Acute Otitis Externa (AOE) within 21 days (3 weeks) prior to screening.
3. Subjects with graded II or III of AOE must experience each of symptoms or signs: as at least 2 for swelling (0-3 scale) and 1 for otorrhea (0-3 scale) and 2 for tenderness (0-3 scale).
4. Willingness to prevent water getting into the ear canal through end of the study (e.g. refrain from swimming, wear shower caps to cover the ears during showers).
5. For adult subjects, ability to fully understand the clinical trial and provide written informed consent. For subjects under the legal age (≥8 years and <18 of age) and capable of giving informed consent, informed consent form sign by both the subject and the parent/legal guardian. For subjects under 8 years of age, signed consent form from the parent/legal guardian.
6. For females of childbearing potential (including partners of male subjects), not planning a pregnancy during the study and agree to use adequate birth control methods (from screening until 28 days after the final dose).

Exclusion Criteria:

1. Subjects with bilateral AOE
2. Subjects who can't accept otoscopy (≤6 years of age) or oto-endoscope (>6 years of age).
3. Previous episode of AOE within 4 weeks prior to enrollment, or 2 or more episodes of AOE within 6 months prior to enrollment.
4. Tympanic membrane perforation (including tympanostomy tubes).
5. Known or suspected of fungal or viral ear infections, cholesteatoma, otitis media, malignant otitis externa, mastoiditis, seborrheic dermatitis, neurodermatitis in the external ear canal, ear trauma or other non-infectious suppurative ear diseases.
6. Known or suspected of hearing loss.
7. History of malignant tumors in the external ear canal, or currently receiving chemotherapy or radiotherapy.
8. Current diagnosis of diabetes mellitus, psoriasis, immunodeficiency or history of drug abuse.
9. Current diagnosis of cardiovascular, respiratory, urinary, gastrointestinal and neurological diseases which require intervention after at least 4 weeks of drug therapy.
10. Use of any systemic antibacterial or topical antibiotic, corticosteroids, analgesic and anti-inflammatory drugs and other drug that affect the study results within 1 week prior to screening.
11. Known or suspected hypersensitivity to quinolones, corticosteroid or any component of the study medication.
12. Participation in another clinical trial within the previous 3 months.
13. Pregnant women or nursing mothers.
14. Any condition that, in the judgment of the principal investigator, render the subject not suitable for the study.