Abstract: In greenhouse,oneyearold seedlings of bald cypress(Taxodium distichum L.)grown in pots containing soils were subjected to salinity(NaCl) treatments.Salinity level is 0.00%,0.15%,0.30% and 0.45% of soil dry weight.After eight weeks of treatment,height growth,diameter growth,leaf water potential,leaf relative water content,leaf relative water deficiency,tissue density,chlorophyll content,relative membrane permeability,free proline content and protein content were determined.The results were as follows:(1)With the increasing of salinity concentration,the height growth and diameter growth decreased,especially the treatments of 0.30% and 0.45% decreased significantly,and the height growth of the two treatments is only 38.3% and 59.1% of control treatment,and the diameter growth is 52.1% and 69.9% of control treatment;(2)With the increasing of salinity concentration,proline content,membrane permeability,tissue density and relative water deficiency decreased gradually,but water potential,chlorophyll content,protein content and relative water content increased;(3)The relation between the physiological indexes determined and the growth of height and diameter is very close,and their relative coefficients are all more than 0.834 and 0.850.