This is a multicenter, double-blind, randomized, placebo-controlled study conducted in overweight or obese subjects. This study is divided into the first stage and the second stage. The participant enrollment and data analysis in the two stage are independent and do not influence each other.

In the first stage of this study, about 240 subjects will be enrolled. Qualified subjects will receive placebo in a 2-week introduction period, after that, they will be randomized to IBI362 low dose, IBI362 moderate dose, IBI362 high dose groups, in every group, subjects will be randomized to IBI362 and placebo groups at a ratio of 3:1. Random stratification is performed based on BMI < 28.0 kg/㎡ and BMI≥28.0 kg/㎡. The subjects received drug administration once weekly. The entire trial covers a 3-week screening period, a 2-week placebo introduction period, a-24 week double-blind treatment period, and a 12-week drug discontinuation follow-up period. During the entire research period, the subjects shall maintain diet and exercise control.

The second stage is IBI362 extra high dose study, about 80 subjects will be enrolled. Qualified participants will receive placebo in a 2-week introduction period, after that, they will be randomized to IBI362 extra high dose and placebo groups at a ratio of 3:1. The subjects received drug administration once weekly. The entire trial covers a 3-week screening period, a 2-week placebo introduction period, a 24-week double-blind treatment period, a 24-week extended treatment period, and a 12-week drug discontinuation follow-up period. The 24-week extended treatment period is optional. During the entire research period, the subjects shall maintain diet and exercise control.

Inclusion Criteria:

1. The first stage: Body mass Index (BMI) ≥28 kilograms per square meter (kg/m²), or ≥24 kg/m² with at least one of the following comorbidities: hyperphagia, pre-diabetes, hypertension, dyslipidemia, fatty liver disease, weight-bearing joint pain, obesity-induced dyspnea or obstructive sleep apnea syndrome; The second stage: Body mass Index (BMI) ≥30 kilograms per square meter (kg/m²)
2. The weight change of the subjects before and after the introduction period was less than 5.0%

Exclusion Criteria:

1. Diabetes mellitus
2. Weight change > 5.0% after diet and exercise control for at least 12 weeks before screening
3. Have used or are currently using weight loss drugs within 3 months before screening
4. History of pancreatitis
5. Family or personal history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN-2)
6. History of moderate to severe depression，or have a history of serious mental illness
7. Any lifetime history of a suicide attempt