Abstract: The effect of salicylic acid （SA） supply （0.01， 0.05， 0.1 mmol/L） on the antioxidant resistance and changes of reactive oxygen species （ROS） in ‘Nanlin 895’ poplar plantlets （Populus delotides×P. euramericana cv. ‘Nanlin 895’） in vitro was investigated under treatment 100 mmol/L NaCl. The results showed that exogenous SA significantly enhanced five antioxidant enzymes activities including superoxide dismutase （SOD）， catalase （CAT）， peroxidase （POD） except in leaves， ascorbate peroxidase （APX） and glutathione reductase （GR）， and also increased the content of ascorbic acid （AsA） and reduced glutathione（GSH）. However SA significantly alleviated active oxygen damage （e.g. O〖DD（-*2〗-〖〗·〖DD）〗2， H2O2） in leaves and roots， reduced the generation of MDA in leaves. These results suggest that exogenous SA could improve activity of protective enzymes， and ameliorate the negative effect of salinity on poplar growth. Poplar roots and leaves showed different mechanisms of scavenging ROS during the application of SA under salt stress. The ascorbateglutathione pathway is related to scavenging H2O2 in polar leaves while peroxidase are responsible for scavenging H2O2 in poplar roots. 0.01-0.05 mmol/L SA treatments could obviously alleviate salinity injury of ‘Nanlin 895’ poplar plantlets.