The purpose of this research study is to compare the efficacy and safety of SCT630 and adalimumab (HUMIRA®) in adults with plaque psoriasis.

Inclusion Criteria:

1. Men or women ≥ 18 and ≤ 70 years of age at time of screening.
2. History of psoriasis for at least 6 months ,and stable moderate to severe plaque psoriasis within 2 months prior to randomized.
3. Moderate to severe psoriasis defined at screening and baseline by：Body surface area (BSA) affected by plaque psoriasis of 10% or greater, and PASI score of 12 or greater, and static physician's global assessment score of 3 or greater.
4. Negative test for Interferon-gamma-release assay an chest X-ray at time of screening.
5. Subject is a candidate for systemic therapy or phototherapy procedures.
6. Female participants must have a negative pregnancy test; are not planning to become pregnant; and must not be lactating.
7. From the screening period to the end (Six months after the last administration),female participants must agree to employ a highly effective contraceptive measure.

Exclusion Criteria:

1. Other forms of psoriasis,skin conditions(eg, eczema) or systemic autoimmune diseases which affected the evaluation of treatment outcomes .
2. Received local anti-psoriasis drugs within 2weeks prior to baseline;
3. Received PUVA ,UVB or non-biologics within 4weeks prior to baseline,including methotrexate,Cyclosporine,tretinoins,traditional Chinese medicine,and so on.
4. Received etanercept or its biosimilars within 4weeks prior to baseline.
5. Received other anti-TNF ,IL-12/23inhibitors or IL-17inhibitors within12months prior to baseline.
6. Be receiving or had received any biologics ≤ five half-lives.
7. Patients who previously used adalimumab or a biosimilar of adalimumab ineffectively or intolerantly.
8. History of tuberculosis, active tuberculosis or latent tuberculosis infection.
9. Suffering from active infection or history of infection :Systemic anti-infective therapy was performed 4 weeks before screening, severe infections with hospitalization or intravenous anti-infective treatment within 8 weeks before screening or recurrent, chronic or other active infections which were assessed by researchers to increase the risk of subjects.
10. Subjects were known to have malignant tumors or a history of malignant tumors (except for skin squamous cell carcinoma in situ, basal cell carcinoma, cervical cancer in situ, or skin squamous cell carcinoma with no evidence of recurrence after thorough treatment, or five years prior to investigational product administration)
11. Moderate to severe congestive heart failure (New York Heart Association Classes III or IV）.
12. Subjects with a significant disease other than psoriasis and/or a significant uncontrolled disease (such as, but not limited to, nervous system, renal, hepatic, endocrine, hematological, autoimmune or gastrointestinal disorders)，and which were assessed by researchers to increase the risk of subjects.
13. Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) > 2.5 times upper limit of normal (ULN) ,Hemoglobin < 90 g/L ,Leukocyte count < 3.5×109/L,Platelets < 100×109/L ,Serum creatinine > 2.5 times upper limit of normal (ULN) at Screening.
14. Received any live vaccines ≤4 weeks prior to investigational product administration,or patients who are expecting to receive any live vaccines during the trial.
15. Subjects had hypersensitivity to test drugs and their excipients, or drugs with the same pharmacological and biological classification as test drugs, and had a history of allergy to active substances or excipients of adalimumab or SCT630.
16. Positive test for anti-nuclear antibody(ANA) or anti-double-stranded DNA antibody at screening.
17. Subjects were accompanied by active neuropathy, including but not limited to multiple sclerosis, Guillain-Barre syndrome, optic neuritis, transverse myelitis, or neurological symptoms suggesting demyelinating lesions of the central nervous system.
18. Positive test for HIV antibodies, hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibodies ,or Treponema pallidum antibody at screening.
19. The results of five tests for hepatitis B virus infection should be further tested for hepatitis B virus DNA, if it is greater than or equal to the upper limit of the reference value of each hospital.
20. Women who are pregnant or nursing.