The purpose of this study is to evaluate the Exposure-Response Relationship Between the Plasma Drug Concentrations and the Change From Baseline in QTc interval of a single oral dose of FXS5626 in healthy subjects.

Inclusion Criteria：

1. Healthy, adult, male or female,18-45 years of age (inclusive), with a Body Mass Index (BMI) of 19.0-28.0 kg/m2 (inclusive),have a minimum weight of at least 50kg(male) or 45kg(female).
2. Medically healthy with no clinically significant medical history, physical examination,laboratory profiles, vital signs or ECG abnormalities , as deemed by the PI or designee.
3. Understands the study procedures in the informed consent form (ICF), and be willing and able to comply with the protocol.
4. Female subjects of childbearing potential and male subjects with a partner of childbearing potential who voluntarily signed ICF should be no fertile, sperm/egg donation for 3 months from the beginning to the last dose, and voluntary use highly effective contraception (including partner) (non-drug contraception is required during the trial).

Exclusive Criteria:

1. Female subjects who are pregnant,or breastfeeding,or with a positive pregnancy test
2. Allergic constitutions (such as allergies to two or more drugs, foods, and pollen), or determined by the investigator, may be allergic to the investigational product or any component of the investigational product.
3. Subjects with a prior or present history of clinically abnormal metabolic, liver, kidney, hematological, pulmonary, cardiovascular, gastrointestinal, urinary, endocrine, neurological, or psychiatric disease who were judged by the investigator to be unsuitable for participation in this study.
4. Subjects who have a history of other risk factors for tachycardia, or a family history of a first-degree relative (i.e. biological parent, sibling, or child) of short QT syndrome, long QT syndrome, or sudden unexplained death in young age (≤40 years).
5. Significant screening ECG abnormalities,QTcF interval > 450ms (Fridericia's correction), or QRS>120ms,or PR interval >=210ms or <=120ms
6. Subjects who have got severe infections within 2 months before screening; Or have a history of active bacterial infection or viral infection or fungal infection within 2 weeks before screening
7. Subjects virus serological test (hepatitis B virus surface antigen, hepatitis C virus antibody, human immunodeficiency virus antibody, treponema pallidum specific antibody TPPA) positive results.
8. Subjects with a history of drug abuse,or who screened positive for drug abuse.
9. Subjects who consumed more than 14 units of alcohol per week in the 6 months prior before screening (1 unit of alcohol =360mL beer or 45mL spirits with 40% alcohol or 150mL wine) or had a positive alcohol breath test or could not abstain during the trial.
10. Subjects who smoked more than 5 cigarettes per day in the 6 months prior before screening or could not give up during the trial.
11. Subjects who have abnormal laboratory test: neutrophil count<1.5 x10^9/L,or white blood cell count<3.5 x10^9/L,or creatine kinase greater than the upper limit of normal at screening.