To explore the physiological regulation of exogenous salicylic acid (SA) on Helianthus tuberosus under ClO₄^- stress,salt-tolerant Helianthus tuberosus L. from three different sites in Xuzhou,Weifang,and Nanjing were used as materials. The effects of exogenous SA on growth,root vitality,photosynthesis,and antioxidant capacity under 50 mmol/L NaClO₄ stress were studied by using foliar application and nutrient solution culture to cultivate plants. The results showed that ClO₄^- stress had different degrees of toxic effects on the growth and development of Helianthus tuberosus seedlings. Spraying exogenous SA could effectively reduce the stress damage to the plants,with similar change trend in Helianthus tuberosus L. from different sites. The biomass content,leaf area,plant height,and root length,as well as the chlorophyll content and fluorescence parameters of the leaves increased significantly,and achieved the maximum alleviation effect under SA spraying every day,while the root activity was better under the SA treatment every two days. At the same time,the content of H₂O₂ showed an increasing trend with the increases of SA spraying frequency. The increase in H₂O₂ content of each species was 47.69% when spraying SA every three days,while the increase rate was 50.93% for every two day,and 56.80% for every day. The activities of superoxide dismutase (SOD),peroxidase (POD) and catalase (CAT)were increased,and the content of both malondialdehyde (MDA) and free proline were significantly decreased (P<0.05),indicating that SA induced H₂O₂ to act as a signaling molecule to enhance the tolerance of plants in the ClO₄^- environment. The grey correlation analysis showed that the application of SA had the greatest influence on the chlorophyll fluorescence parameters and root activity of perchlorate stress. In summary,foliar application of 50 μmmol/L SA mainly affected the leaves and roots of Helianthus tuberosus. The ClO₄^- stress damage could be relieved by stimulating H₂O₂ to participate in the changes of antioxidant enzymes,and regulating the osmotic adjustment ability of plants to protect the photosynthesis and root activity. Spaying SA every day had the best effect. These findings would provide a basis for the further exploration of Helianthus tuberosus in ClO₄^- contaminated soil.