• Aged 18 to 75 years at the screening period.

• Presence of wheals with itching for ≥ 6 weeks prior to randomization. At the screening visit, subjects had taken double or more than the approved dose, or a combination of two or more H1 antihistamines for the treatment of chronic spontaneous urticaria for at least 2 weeks. Within the 7 days preceding randomization, the Urticaria Activity Score 7 (UAS7) was ≥16 (range 0-42), Itch Severity Score 7 (ISS7) was ≥8 (range 0-21), at least one UAS (range 0-6) was ≥4 on any screening visit day, and there must be a current record of medication use.

• Subjects must not miss more than one diary record (morning or night) within 7 days prior to randomization (day 1), and are willing and able to complete daily symptom electronic diary records during the study period;

• Male participants and their partners or female participants must agree to take one or more non pharmacological contraceptive measures (such as complete abstinence, contraceptive ring, partner ligation, etc.) during the trial period and within 6 months after the end of the trial and have no plans for sperm or egg donation.

• Agree to participate in this clinical trial and voluntarily sign an informed consent form.