Inclusion Criteria:
1. between 6 and 18years of age at time of screening.
2. Chronic plaque-type psoriasis present for at least 6 months and diagnosed before randomization.
3. Moderate to severe psoriasis as defined at Baseline/ randomization by:
PASI score of 12 or greater, and sPGA score of 3 or greater (based on a static scale of 0 - 5), and Body Surface Area (BSA) affected by plaque psoriasis of 10% or greater.
Exclusion Criteria:
1. Forms of psoriasis other than chronic plaque-type (e.g., pustular, erythrodermic and guttate psoriasis) at Screening or Baseline/randomization.
2. Drug-induced psoriasis.
3. Had a clinically significant flare of psoriasis during the 12 weeks prior to baseline (Week 0).
4. Presence of other skin conditions (e.g. skin infections, seborrheic dermatitis) that in the judgement of the Investigator could interfere with assessment of psoriasis.
5. History of inflammatory bowel disease or have other ongoing active autoimmune diseases.
6. At screening, history or symptoms of malignancy of any organ system, treated or untreated, within the past 5 years, regardless of whether there is evidence of local recurrence or metastases.
7. History of congestive heart failure (New York Heart Association \[NYHA\] functional classification ≥III), cerebro-cardiovascular events, or serious bleeding events at screening and / or randomization that in the judgement of the Investigator prevents the subject from participating in the study.
8. Active systemic infections (other than common cold) during the 4 weeks before randomization (e.g., hepatitis), or serious infections requiring hospitalization and/or intravenous injection of antibiotic treatment within eight weeks prior torandomization.
9. History of depression and/or suicidal ideation or any suicidal behavior based on an assessment with the Columbina Suicide Severity Rating Scale (C-SSRS) at screening and baseline (Posner K et al, 2011), The subjects will be exluded if any answer to question is "yes" in the questionnaire orare clinically judged by the investigator to be at risk for suicide.
10. All subjects will be tested for tuberculosis status using IGRA and X-ray test.
11. Have evidence of positive test for hepatitis B, hepatitis C antibody, or human immunodeficiency virus (HIV) antibodies.
12. Have a known allergy or hypersensitivity to any biologic therapy at screening that would pose an unacceptable risk to the subject if participating in this study.
