This study is a multicenter, randomized, double-blind, placebo-controlled Phase II clinical trial, aiming to evaluate the efficacy, safety, and tolerability of CMS-D001 in participants with moderate to severe atopic dermatitis, as well as to assess the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of CMS-D001 and its major metabolites (as applicable) in participants with moderate to severe atopic dermatitis, so as to provide a basis for the dosage of the Phase III confirmatory clinical trial.