Inclusion Criteria:
* ≥2 to\<12 years of age at the time of randomization, males or females.
* Patients in the screening period met the following criteria:
1. Rapid influenza diagnostic test (RIDT) or polymerase chain reaction (PCR) test positive;
2. Axillary temperature ≥ 37.5℃ at screening; If taking antipyretics, axillary temperature ≥ 37.5℃ after taking the drug (more than 4 hours).
3. At least one of the influenza-related respiratory symptoms is moderate or greater in severity: nasal congestion/runny nose and coughing.
* The first occurrence of influenza symptoms ≤ 48 hours from the time of patient randomization. The occurrence of symptoms is defined as:
1. The body temperature first reached ≥ 37.5℃ (axillary/oral temperature) or 38.0℃ (rectal or tympanic temperature);
2. Or the occurrence of at least one systemic or respiratory symptom: nasal congestion, sore throat, cough, muscle pain, headache, etc.
* The guardian of the participants must agree to participate in the study and sign a written informed consent form. For participants aged 8 years old and above, they must sign the informed consent form voluntarily (for participant under the age of 8, only the informed consent form signed by the guardian is required.); The participant s and/or their guardians agree to comply with all study procedures, including filling out the participant diary cards (the guardians of the subjects may assist in the assessment/filling).
Exclusion Criteria:
* Patients with severe or critically influenza virus infection (Meet any one of the following criteria).
1. Severe cases with any of the following conditions： Dyspnea and/or increased respiratory rate: more than 30 breaths per minute for children over 5 years old; over 40 times per minute for children aged 2 to 5.
Changes in consciousness: slow response, drowsiness, restlessness, convulsions, etc.
Severe vomiting or diarrhea, with signs of dehydration. oliguria: Children with urine output\<0.8 mL/(kg · h), or infants with daily urine output\<200 mL/m2, preschool children\<300 mL/m2, school aged children\<400 mL/m2, or experiencing renal failure;
2. Critical cases with any of the following conditions (Including but not limited to)： Respiratory failure; Acute necrotizing encephalomyopathy; Shock septic; Multiple organ dysfunction; Other serious clinical situations require intensive care Note: Refer to \<the Expert Consensus on Diagnosis and Treatment of Childhood Influenza (2020 Edition)\>
* High risk population for severe cases (meeting any of the following criteria):
1. Accompanied by the following underlying diseases, and being clinically significant according to researchers' judgment, such as lung diseases (asthma, tracheopulmonary dysplasia, cystic fibrosis, etc.), liver diseases, kidney diseases, hematological diseases, heart diseases (congenital heart disease, chronic congestive heart failure \[NYHA heart function classification III-IV\], etc. But excluding hypertension without any other heart related symptoms), neurological and neuromuscular diseases that affect respiratory secretion clearance function (cognitive impairment, spinal cord injury, epileptic seizures, neuromuscular disorders, and cerebral palsy, etc), metabolic and endocrine system diseases.
2. Immunocompromised individuals, such as patients with malignant tumors, organ or bone marrow transplants, HIV infections, or those who have been taking immunosuppressive drugs in the past 3 months.
3. The electrocardiogram shows clinically significant QT corrected interval abnormalities (QTc ≥ 460ms) (QT corrected interval calculated according to Fridericia's formula, i.e. QTcF).
4. Subjects require long-term use of aspirin or salicylate containing defined as those who need to take aspirin or salicylate containing drugs regularly per day for more than 14 days.
5. With a body mass index (BMI) exceeding the criteria outlined in Appendix 2 of this protocol; During the screening period, patients with clinically significant bronchitis, pneumonia, pleural effusion, or interstitial lesions that identified by the researchers. If the researcher deems it necessary, imaging examinations (chest X-ray or chest CT) can be performed.
* Individuals who have experienced acute respiratory infections or otitis media and sinusitis within the past 2 weeks prior to screening.
* Combined with other respiratory infections, or requiring systemic anti infection treatment, or blood routine examination during screening with white blood cell count (WBC)\>ULN (venous blood).
* Coughing up purulent phlegm or suffering from purulent tonsillitis.
* Have difficulty in swallowing medicine or have a history of gastrointestinal diseases that determined by researchers to seriously affect drug absorption.
* Suspected allergy to the active ingredients or excipients of the investigational drug.
* Have taken anti influenza virus drugs (including but not limited to: neuraminidase inhibitors, hemagglutinin inhibitors, M2 ion channel blockers, and cap structure dependent endonuclease (CEN) inhibitors, such as oseltamivir, zanamivir, paramivir, favipiravir, rimantadine, amantadine, abiidol, balosavir, etc.) within the past 7 days prior to screening.
* Received live or attenuated vaccines within the first 2 weeks of randomization or subjects who have received influenza vaccine within the first 2 weeks of randomization;
* Suspect or have a history of alcohol or drug abuse.
* Positive in pregnancy test.
* Participated in other clinical trials and used any other clinical trial drugs or devices within the 30 days prior to screening;
* Determined by the researchers to be unsuitable for participation in this clinical study.
