Introduction: Adalimumab has been used successfully in the treatment of psoriasis. The objective of the study is to compare the efficacy, safety, and immunogenicity between HLX03, an adalimumab biosimilar, and adalimumab in Chinese patients with moderate-to-severe plaque psoriasis. Methods: In this double-blind, active-controlled, parallel-group study, 262 patients with moderate-to-severe plaque psoriasis were randomized (1:1) to receive HLX03 or adalimumab (80 mg at week 1, 40 mg at week 2, and then 40 mg every 2 weeks) for 48 weeks. The primary endpoint was improvement in Psoriasis Area and Severity Index (PASI) score at week 16 comparing to baseline. Equivalence was demonstrated if 95% confidence interval (CI) of the between group difference fell within the equivalence margins of +/- 15%. Other efficacy endpoints, safety and immunogenicity were also evaluated. Results: In the full analysis set, PASI improvements at week 16 was 83.5% (n = 131) in the HLX03 group and 82.0% (n = 130) in the adalimumab group, with a least-square-mean difference of 1.5% (95% CI - 3.9% to 6.8%). There were no significant between-group differences in all secondary efficacy analyses including proportion of patients achieving >= 75% improvement from baseline PASI (PASI 75), physician global assessment (PGA) 0/1 (clear or almost clear) and change in dermatology life quality index (DLQI) score. The incidences of adverse events and the proportion of patients with antidrug antibodies were also comparable between the two treatment groups. Conclusion: HLX03 demonstrated equivalent efficacy, similar safety and immunogenicity to reference adalimumab, supporting its development as an alternative treatment for patients with plaque psoriasis in China.