Abstract: The accumulation of sugar, starch, and nicotine in oriental tobacco leaves were investigated in Baoshan oriental tobacco growing areas of Yunnan Province.The results showed that oriental tobacco growing in winter and spring featured higher total sugar content and sugar/nicotine ratio, and lower nicotine content comparing with that in the tobacco growing in summer;the starch content was increased and nicotine content was almost unchanged, even slightly decreased during the growing and developing of winter-spring oriental tobacco.Higher sugar matter accumulation and lower nicotine accumulation in winter-spring oriental tobacco leaves might be related to growing season.