〔Abstract〕 Objective Differential expression of the transcription factor Sp1 was compared in skin tissues and epidermal keratinocytes of psoriasis and normal controls to verify its correlation with the pathogenesis of psoriasis and to explore its clinical significance. Methods Immunohistochemical staining, real-time quantitative PCR and Western blot were used to detect the expression and distribution of Sp1 in mRNA and protein levels in skin tissues of psoriasis vulgaris group and normal control group; After processing Sp1 gene in Hacat cells, the cell proliferation function was detected. Results Immunohistochemical staining showed Sp1 expression was higher in the psoriasis group than that in the normal control group. The psoriasis group was widely expressed in the nucleus of each layer of the epidermis, mainly in the spinous layer and basal layer. Molecular studies showed the expression of Sp1 in mRNA and protein levels of psoriasis group was significantly higher than that of normal control group(P<0.05). After treatment with gene knockdown technology, Hacat cells were subjected to absolute cell counting and CCK-8 counting. The cells in the knockdown group grew slowly and the number of cells decreased, suggesting that Sp1 could promote the proliferation of keratinocytes. Conclusion There may be a correlation between Sp1 and the pathogenesis of psoriasis. The high expression of Sp1 in the skin lesions of patients with psoriasis may participate in the pathogenesis of psoriasis by promoting the proliferation of keratinocytes. At the same time, the expression of Sp1 can provide some reference values for evaluating the biological behavior and treatment effectiveness of psoriasis.