to understand impact of Erda Guizhi Extract on IL-18 expression in plasm of keratodermia patients. Methods:Concentration of IL-18 of the treatment group(90cases) and the control group(90cases)were detected before and after treatment by Enzyme Linked Immuno-sorbent Assay(ELISA) and compared with healthy control(90cases). Results:Before treatment, the treatment group was significantly different with the healthy control(P<0.01); Improvement was significant for the treatment group after treatment(P<0.01); so was differences between the treatment and control group(P<0.01).Conclusions:Erda Guizhi Extract is more favorable than the control group in treating keratodermia by cutting down IL-18 expression in plasm of keratodermia patients. The experiment provides new thoughts of thinking for further study on pathogenesis and cause of keratodermia, suggesting new methods for treatment.