In this study, a solid state fermentation of cereals with Cordyceps militaris SN-18 was performed for the first time.The effects of fermentation on cereals were investigated in terms of total phenolic and saponin contents, antioxidant activities, through various solvent (80% methanol, 80% ethanol,water) extracts.The results showed compared to the unfermented samples, fermented cereals extracts had higher total phenolic and saponin contents, and greater antioxidant. Among various extracts examined, the methanolic extracts of fermented cereals showed the highest DPPH radical scavenging activities, ABTS radical scavenging activities and reducing power. HPLC analysis was performed for determination of the specific phenolic profile, which revealed shikmic acid, chlorogenic acid, rutin, daidzein, genistein and biochanin A were significantly increased during fermentation. Both correlation analysis and principal component analysis indicated total saponin and phenolic contents were closely related with antioxidant activities. The fermentation process with Cordyceps militaris enhanced antioxidant capacities of cereals and thus was considered of great potential for the food industry.