The present invention provides a use of Imperata cylindrica fermented extract for enhancing the gene expression of Keratin, Filaggrin and Hyaluronan synthase, promoting the proliferation of collagen and elastin, and enhancing antioxidant capacity of skin cells. The Imperata cylindrica fermented extract can effectively increase the moisturizing ability of the skin, maintain the keratinocyte arrangement and the integrity of the stratum corneum structure to enhance the skin barrier function, and make the skin firm and elastic, and prevent skin aging. The Imperata cylindrica fermented extracts is prepared by fermenting the Imperata cylindrica extracts to yeast, and lactic acid bacteria two-staged fermentation.本發明提供一種白茅根發酵物用於提升皮膚細胞角蛋白基因、聚角蛋白微絲基因與玻尿酸合成酶基因表現量、促進膠原蛋白與彈力蛋白增生、及提升抗氧化能力的用途，能有效使皮膚保濕能力上升、維持角質細胞排列、維持角質層結構完整，以提升皮膚屏障功能，並能使皮膚緊緻有彈性，以及防止皮膚老化。其中該白茅根發酵物，係將白茅根水萃取物以酵母菌、及乳酸桿菌進行二段式發酵所製得。
