Abstract: Objective：To investigate the association between serum complement 3 (C3) and metabolic syndrome (MS) in psoriasis patients from Wenshan County of Yunnan Province. Methods：A total of seven hundred and twenty eight psoriasis patients (psoriasis group) and seven hundred and fifty six healthy controls (healthy group) were enrolled from Wenshan County of Yunnan Province. The incidence of MS and C3 level were compared between the two groups. The clinical features and C3 level of psoriasis patients with and without MS were also compared. The related factors of C3 level in psoriasis patients combined with MS were analyzed. Results：The incidences of high fast blood glucose and lipid disorder in the psoriasis group were higher than those in the control group (P<0.05). And the incidence of MS was higher in the psoriasis group than that in the control group (P=0.003). Drinking was a risk factor for comorbidity of psoriasis and MS in patients from Yunnan Wenshan (P=0.013). The serum C3 level of psoriasis patients combined with MS was statistically higher than that in patients without MS (P=0.015). And C3 level was positively correlated with body mass index (BMI), psoriasis area and severity index (P<0.05). And there were significant correlations between C3 level and psoriasis vulgaris and psoriasis arthropathica (P<0.05). Conclusions：In Wenshan County of Yunnan Province, psoriasis patients are more likely to have MS. C3 level is significantly correlated with MS and the severity of psoriasis, especially high in patients with psoriasis vulgaris or arthropathica.