In conclusion, we demonstrated that EGCG attenuates IMQ-induced psoriasis-like inflammation; reduces expression of PCNA; increases expression of caspase-14; reduces infiltrations of T cells in mice skin; regulates the percentages of CD4+T cells and CD11c+ DC of spleens; down-regulates the levels of IL-17A, IL17F, IL-22, IL-23 and malondialdehyde (MDA) in plasma; and increases bioactivities of superoxide dismutase (SOD) and catalase (CAT) in plasma to treat psoriasis. The gene discussed is IL17F; the disease is psoriasis.