The factors influencing the fermentation of Oriental tobacco seed with the strain P1, such as fermentation temperature, time, aeration material and water application, were studied. The highest degradation rate of lipids in Oriental tobacco seed was obtained when the seed was blended with aeration material and fermented at 28° C for ten days, during which water was added at a rate of one half of seed weight on the 4th day. The volatile constituents in Oriental tobacco seed before and after fermentation were analyzed by GC/MS. Forty-three volatile compounds were identified, among them, twenty-six important aroma components did not exist in unfermented tobacco seed, and nicotine in fermented seed was decreased remarkably. The irritation of cigarette smoke was reduced and the smoking quality was significantly improved when the extract of fermented tobacco seed was added into cigarettes.