This is a randomized, double-blind, placebo-controlled, dose-escalation phase I clinical study. A sequential design is used in this trial with a single dose escalation climb test, to investigate the safety, tolerability, and PK/PD characteristics of GZR18 injection in Chinese obese/overweight subjects.

Inclusion Criteria:

• Subjects sign the informed consent form (ICF) voluntarily.
• Chinese adult subjects, both male and female.
• 18 to 65 years old (including both ends) at screening.
• BMI≥26.0 kg/m2 at screening.
• Stable weight before screening (i.e. self-reported weight change less than 5 kg within 8 weeks before screening).
• Female subjects have negative serum Human Chorionic Gonadotropin (HCG) during screening and baseline periods.
• Subjects have good daily habits and can maintain good communication with investigators and comply with various requirements of clinical trials.

Exclusion Criteria:

• Lactating women.
• History of fainting with blood and needles.
• Known or suspected allergy to study related products; or drug/food allergy history; or allergy-related diseases history.
• Subjects who have participated in other clinical trials and given investigational drugs or medical device interventions within 90 days before screening.
• History of drug abuse within 1 year before screening, or positive results in drug abuse screening (urine).
• Smokers who smoke ≥ 5 cigarettes per day within the previous 3 months before screening or cannot refrain from smoking throughout the trial period.
• Any vaccine has been used within 28 days before administration, as well as any vaccine that may be used throughout the trial period.
• Other scenarios judged by the investigator to render the subjects unsuitable for participating in this study.