This study is a randomized, double-blind, placebo- and active-controlled multicenter clinical trial involving patients with moderate to severe plaque psoriasis.

Safety and efficacy assessments will be conducted during the scheduled study visits throughout the trial. After completing the respective treatment, all subjects will undergo a safety follow-up. Both the investigators and subjects will remain blinded throughout the entire treatment period.

During the study, subjects are required to provide blood samples for pharmacokinetic (PK) and pharmacodynamic (PD) analyses at the time points specified in the trial protocol.

Inclusion Criteria:

• The patient voluntarily participates in this study after providing fully informed consent, signs a written informed consent form, and agrees to comply with the procedures specified in the study protocol;
• Aged between 18 and 70 years old (inclusive) at the time of signing the informed consent form, regardless of gender;
• The investigator assesses that the subject has plaque psoriasis suitable for systemic therapy, and the condition has been stable for ≥ 6 months before signing the informed consent form;
• At the screening stage and Day 1 (D1) of the treatment period, the Psoriasis Body Surface Area (BSA) is ≥10%, the Physician Global Assessment (PGA) score is ≥ 3 points, and the Psoriasis Area and Severity Index (PASI) score is ≥ 12 points;
• Hematology, Blood chemistry and Urinalysis examination were basically normal;
• Male subjects and female subjects of childbearing potential must agree to abstain from sexual intercourse or adopt effective contraceptive measures from the time of signing the informed consent form (ICF) until 30 days after the last administration of the investigational product.

Exclusion Criteria:

• Suffering from any type of psoriasis including erythrodermic psoriasis, pustular psoriasis, guttate psoriasis, inverse psoriasis, or drug-induced psoriasis;
• Having other skin lesions that may interfere with the assessment of treatment outcomes, such as eczema;
• A history of severe herpes zoster/simplex infection;
• A history of tuberculosis, active tuberculosis, latent tuberculosis, or clinical manifestations suggestive of tuberculosis infection
• Having language barriers, or being unwilling or unable to fully understand and cooperate;
• Being pregnant or lactating women;
• Other circumstances that the investigator deems unsuitable for the subject to participate in the study.