Abstract: Objective To investigate the correlation between serum IL-31 expression level and severity, pruritus and quality of life in patients with chronic spontaneous urticaria. Methods A total 180 patients with chronic spontaneous urticaria and 60 health examinees admitted to dermatology department of our hospital from December 2015 to December 2018 were selected as the research objects. According to the patient's condition, the patients were divided into mild group (60 cases), moderate group (60 cases) and severe group (60 cases). The difference of serum IL-31 levels in each group was compared. The patients were scored with 7-day comprehensive symptom score, VAS and CU-Q2oL score. The correlation between serum IL-31 level and 7 d symptom score, VAS score and CU-Q2oL score was tested. Results The serum level of IL-31 in healthy subjects (7.63±0.85) pg/mL was significantly lower than that in patients with chronic spontaneous urticaria (25.14±3.50) pg/mL (P<0.05). The serum IL-31 levels in the mild, moderate and severe groups increased in turn Serum IL-31 levels in mild, moderate and severe groups increased in turn (17.66±2.05, 23.70±3.13 and 28.77±3.62) pg/mL, with statistical significance (P<0.05). Person correlation analysis showed that serum IL-31 level was positively correlated with 7-day syndrome score, VAS score and CU-Q2oL score in patients with chronic spontaneous urticaria (r=0.658-0.795, all P<0.05). Conclusion IL-31 may play an important role in the itching mechanism of patients with chronic spontaneous urticaria, and may affect the severity of the lesion and the quality of life after the disease.