Abstract: The experiments on effects of different covering materials on growth and development of flue-cured tobacco seedlings in floating system were conducted in Henan Agricultural University Experiment Station during 2000-2001. The results showed that the vermiculite cover was better than medium cover.The growth of tobacco seedlings was obviously promoted, the root vigor and activity of NR, SOD and INV were improved, and contents of chlorophyll and mineral elements in tobacco leaves were also increased by vermiculite-covering.