Abstract: The influence of waterlogging stress on agronomical and physiological characteristics in flue-cured tobacco at the root extending stage were studied with cultivar yunyan87 under pot experiment with volcanic ash and paddy field soil from Yunnan Province.The results showed that in the same degree of waterlogging stress,agronomical characteristics and root growth of the flue-cured tobacco grown in volcanic soil suffered the adverse effects less than flue-cured tobacco grown in paddy field soil,the suppression suffered serious degree proportional to the stress level.The root activity of two soils is inhibited,but it is no significant difference.Chlorophyll content and NR activity are volcanic ash soil grown flue-cured tobacco higher,but is inversely proportional to the degree of NR activity suppression suffered by the degree of stress.