This is a multicenter, open-label study aim to evaluate the efficacy and safety of IBI112 in Chinese participants with plaque psoriasis who were treated with biologics and switched to IBI112. The study will enroll 160 participants who were diagnosed with plaque psoriasis. The whole study consists of 4 weeks of screening, 32 or 36 weeks of treatment and a safety follow-up visit at Week 44.

Inclusion Criteria:

1. 18 to 75 years old;
2. Evaluated suitable for continuing biologic therapy for plaque psoriasis by the investigator;
3. Received previous biologic therapy with at least 4 months.

Exclusion Criteria:

1. Diagnosed with guttate psoriasis, pustular psoriasis, erythrodermic psoriasis, or drug-induced psoriasis (e.g., psoriasis caused by beta blockers, calcium channel inhibitors, etc.) at screening;
2. Previously treated with IBI112 or other IL-23 inhibitors;
3. Treated with two biologics for psoriasis within 4 months prior to screening;
4. Treated with topical therapy for psoriasis within 2 weeks prior to the first dose administration, or treated with systemic non-biological agents or phototherapy within 4 weeks prior to the first dose administration;
5. Treated with Natalizumab, or B/T cell regulators (e.g., Rituximab, Abatacept, or Visilizumab) within 12 months prior to the first dose administration;
6. Not willing to avoid constant sunshine and other ultraviolet light sources exposure during the study;
7. Treated with an investigational biologic within 6 months prior to the first dose administration, or any investigational therapy within 30 days, or an investigational drug within 5 half-lives, or currently participating in a clinical study.