This study is a randomized, double-blind, dose-escalating phase I clinical study to evaluate the safety, tolerability and pharmacokinetics of 9MW1911 injection in healthy subjects.

Inclusion Criteria:

- 1. Male or female subjects aged 18 to 65 years (including 18 and 65 years). 2. Weight≥50.0 kg for males, or weight≥45.0 kg for females, and body mass index (BMI) in the range of 19.0 ~ 26.0 kg/m2 (including cut-off value).

3. Female subjects must have a negative β-HCG pregnancy test (Screening and Baseline); Subjects(including their partners) will take effective contraceptive measures voluntarily.

Exclusion Criteria:

• 1. Subjects who have a history of allergies to biological agents or any drug components; those who have a history of allergies and judged by the investigator to be ineligible for enrollment.

  2. The clinical laboratory tests show any clinical abnormalities, or abnormalities with clinical significance (including but not limited to diseases of digestive tract, kidney, liver, nervous system, blood, endocrine system, cancer, lung, immune system, mental, heart) , and judged by the investigator to affect participation in this study.

  3. Subjects with prolonged QTcF interval (> 450 ms) on electrocardiogram (ECG) examination, or family history of prolonged QTc syndrome or sudden death.

  4. Subjects received any biological treatment (including all vaccines except the coronavirus vaccine) within 3 months before screening, or planned to take biological treatment during the study period, or received the new coronavirus vaccine within 1 month before screening.

  5. Subjects received any prescription drugs or traditional Chinese medicines, including vitamins, trace elements or dietary supplements within 14 days before screening; except for topical products without systemic absorption.

  6. Subjects with a history of smoking within 6 months before screening, or unwilling to stop smoking during the study, or willing to use products containing nicotine during the study.

  7. Subjects who have lost blood or donated blood ≥200mL within 3 months before screening, or those who plan to donate blood within 3 months.

  8. Subjects positive screening for viral hepatitis (including hepatitis B and C), HIV antibodies, and Treponema pallidum antibodies.

  9. Subjects who paticipated any clinical trial within 3 months before screening.

  10. Subjects who is inappropriate to participate in the trial due to any reasons as determined by the investigator.