Effects of different rates of selenium ore powders on physiological characteristics,qualities and selenium accumulation of tobacco seedling were studied by applying selenium ore powders in the nursery pond during seedling stage.The results showed that it significantly improved the growing,chlorophyll,soluble sugar content,root activity and the selenium content of tobacco seedling with the using of selenium ore powders.The rising of chlorophyll and droping of stomatal limitation were probably the reasons of increasing net photosynthetic rate by applying of selenium ore powders in low dosage and the decreasing of net photosynthetic rate was probably determined by stomatal factors under high dosage.Under the conditions of this study,it was proper to applying selenium ore powders of 246 kg per hectares during seedling stage.