This article was to examine the pharmacological effects of optimized Decoction of Yinxieling(YXLOD) in treating psoriasis in mouse psoriasis models and in vitro. Female mice were made high estrogen cycle model for mitotic rate calculating in virginal epithelium. Granular layer formation was calculated in mice tail scales. YXLOD was administrated by gavage for 9 days and 15 days in two models, respectively. Human keratinocyte HaCaT cells were cultured as in vitro to detect the effect of YXLOD on epithelial cell growth. Our results shows YXLOD could significantly inhibit the mitosis of mouse vaginal epithelium and promote the formation of granular layers in mouse tail- scale epidermis when compared with saline group, and YXLOD could inhibit HaCaT cell growth signally after treated for 24h. The mechanism of YXLOD in treating psoriasis may be related to promoting granular cell growth and inhibiting proliferation of epidermis cells. Our research may provide some basis for YXLOD on its further clinical application.