【Abstract】 Objective To explore the expression and mechanism of cysteine-rich angiogenic inducer 61 (Cyr61) in skin lesions of patients with psoriasis vulgaris. Methods Skin samples from 38 patients with psoriasis vulgaris and 18 normal persons were collected as psoriasis group and control group. Cyr61 mRNA and protein expression in skin tissues were detected by qRT-PCR and Western blot, respectively. Cyr61 gene was silenced (siCyr61) by RNA interference in a TNF-a-stimulated psoriatic cell model in vitro, and an unrelated sequence was designed as control (siControl). CCK-8, qRT-PCR, Western blot, Elisa were used to detect cell proliferation, inflammatory factor secretion and NLRP3 inflammatory body expression, respectively. Results The expression of Cyr61 mRNA and protein in psoriatic skin was significantly higher than that in control skin (P＜0.001). Compared with the TNF-a + siControl group, the proliferation of cells was significantly inhibited at 48h and 72h after treatment in the TNF-a + siCyr61 group (P＜0.001). The expression of IL-1β，IL-17, IL-22, CXCL1 mRNA in the cells and the contents of IL-1β，IL-17, IL-22, CXCL1 in the supernatant were all decreased in the TNF-a+siCyr61 group (P＜0.05). The protein expression of NLRP3 and mature-Caspase- 1 was significantly decreased in the TNF-a + siCyr61 group (P＜0.001). Conclusion Cyr61 is highly expressed in the skin lesions of patients with psoriasis vulgaris. The silencing of Cyr61 gene by RNA interference can reduce the proliferation and inflammatory factor secretion of TNF-a-induced HaCaT skin cells, which may be related to inhibiting excessive activation of NLRP3 inflammasome.