The trial is conducted in a single-center, randomized, double-blind, placebocontrolled, dose-increasing design. To evaluate the safety, tolerability, pharmacokinetics(PK) characteristics, efficacy and immunogenicity of PB-119 injection in Chinese obese subjects.

The trial is conducted in a single-center, randomized, double-blind, placebocontrolled, dose-increasing design. To evaluate the safety, tolerability, PK characteristics, efficacy and immunogenicity of PB-119 injection in Chinese obese subjects. The study consists of 1-2 cohort . 32 patients are planned to be included in each cohort (24 patients receive study drug，8 patients receive placebo) Subjects will receive treatment for 20 weeks after screening and complete 4 weeks of safety follow-up.

Inclusion Criteria:

1. Chinese male or female subjects aged 18-60 years (both inclusive).

2. Body weight ≥70 kg(male) or 60 kg(female), and body mass index (BMI)

   ≥30.0 kg/m2 at screening.

3. Weight change <5% in the past 3 months before screening.

Exclusion Criteria:

1. Fasting Plasma Glucose（FPG） ≥7.0mmol/L or glycosylated hemoglobin (HbA1c) ≥6.5% or diagnosed diabetes
2. FPG <3.9 mmol/L at screening and/or a history of hypoglycemia.
3. History of Cushing's syndrome, polycystic ovaries, or other hereditary endocrine disorders, or obesity caused by secondary factors such as cortisol hormones.
4. Abnormal Thyroid-Stimulating hormone(TSH), Serum Free Triiodothyronine（FT3）, Serum Free Thyroxine（FT4） or diagnosed thyroid dysfunction
5. History of multiple endocrine neoplasia syndrome type 2 (MEN-2) , medullary thyroid carcinoma (MTC) or Category 4 and above thyroid nodules by Thyroid ultrasound Chinese Ultrasound Thyroid Imaging Reporting and Data System （C-TIRADS）
6. Diagnosed cardiovascular and cerebrovascular diseases with obvious clinical significance within 6 months before screening
7. Systolic blood pressure > 160 mmHg and/or diastolic blood pressure > 100 mmHg at screening or randomization.
8. Time history from the starting point of P-wave to the starting point of QRS wave（PR intervals ）> 210 msec and/or QRS complex（QRS） > 120 msec and/or Corrected QT Interval（QTcF） > 450 msec at screening or randomization.
9. Serum amylase or lipase > 3× upper limit of normal (ULN) at screening or before randomization, or previously diagnosed acute/chronic pancreatitis.
10. Low density lipoprotein cholesterol(LDL-C) ≥4.40 mmol/L or triglyceride (TG) ≥5.65 mmol/L.
11. Use of any approved or unapproved drugs or products that have an effect on body weight within 3 months prior to screening
12. History of bariatric surgery for weight loss before screening.