Abstract: Pot experiments were conducted to research vegetative and physiological changes of Prunus maritima seedlings under NaCl stress. The results showed that its biomass was firstly increased, and then decreased with an increase in NaCl concentration, and its growth was restrained under high level of salinity. Contents of MDA, relative electric conductivity in its leaves were increased to different extents and so were contents of both proline and soluble protein; and the activity of superoxide dismutase, of peroxidase, of root reached a maximum under 6 g/L NaCl in the irrigation water, then reduced significantly at 9 g/L. Changes of net photosynthetic rate, of water use efficiency, of apparent photosynthetic electron transport rate, and of real photochemical efficiency were similar to those of the two enzymes, and also achieved maximun under 6 g/L NaCl, while alterations of intercellular CO2 concentration were contrary to those of the above photosynthetic indexes. In summary, Prunus maritima has high salt resistance, and grows well under condition that NaCl concentration is about 6 g/L.