Background Studies have found that there is relationship between intestinal flora and the occurrence of psoriasis, but the causal relationship between oral flora and psoriasis is not clear.Objective To explore the relationship between the oral microbiome and psoriasis using the two-sample Mendelian randomization method. Methods Single nucleotide polymorphism (SNP) data for oral microbiome exposure and psoriasis outcomes were sourced from China National GeneBank DataBase and NHGRI-EBI GWAS Catalog. MR analysis was conducted using five regression models: MR-Egger, weighted median, inverse variance weighted (IVW), simple, and weighted models. Cochran's Q test, MR-PRESSO, and MR-Egger intercept were used to assess horizontal pleiotropy and heterogeneity. Results This study revealed that in the oral microbiome: Streptococcus infantis.1655 (OR=1.347, P=0.005) and Veillonella.1075 (OR=1.243, P=0.009) were positively correlated with psoriasis. In contrast, Pauljensenia. 1019 (OR=0.767, P=0.039), Pseudopropionibacterium. 291 (OR=0.769, P=0.036), Centipeda. 389 (OR=0.797, P=0.006), an unclassified microbiota.3196 (OR=0.799, P=0.008), and Streptococcus pseudopneumoniae.G.1360 (OR=0.833, P=0.034) were negatively correlated with psoriasis.Conclusion Veillonella. 1075 increases the risk of psoriasis, while Pauljensenia. 1019, Pseudopropionibacterium.291, and Centipeda.389 reduce the risk of psoriasis, however, they show no reverse causal relationship with psoriasis.