Abstract: To elucidate the best transplanting data of main flue-cured tobacco cultivar K326 in tobacco-growing regions of southern Shaanxi province, an experiment evaluating transplanting date was carried out in Xunyang county. The results showed that with postponement of transplanting date of flue-cured tobacco, all main growth dates were put off;field growth period after transplant became shorter. In addition, contents of nitrogen, potassium, chlorophyll and carbohydrate as well as net photosynthesis rate (Pn) of tobacco leaves at key three growth stages i.e. vigorous growing. topping and mature stages were enhanced firstly and then declines. Yield, average price, output value and percentage of medium and superior tobacco leaves showed the similar laws as the above parameters. Based on comprehensive analysis, May 10 was the best appropriate transplanting date of K326 in Xunyang as a representative location of the same altitude area according to the climatic conditions of this area. To determining the best appropriate transplanting date can improve nitrogen and potassium nutrition and increase photosynthetic efficiency for dry matter accumulation resulting in better yield and quality of flue-cured tobacco leaves.