Abstract: To explore effect of exogenous melatonin(MT) on Potentilla anserine L.seedlings under salt stress, this study used Potentilla anserine L. seedlings as materials and measured its growth and physiological indexes after separately applying 0, 12.5, 25, 50, and 100 μmol/L of exogenous melatonin under 200 mmol/L NaCl treatment. The results showed that under salt stress, the indexes such as plant height, leaf length, leaf width, fresh weight, and dry weight of Potentilla anserine L. seedlings treated with exogenous melatonin were somewhat increased compared with those of the untreated seedlings, and the content of osmotic adjustment substances and the activity of antioxidant enzymes were significantly increased, while the content of photosynthetic pigments also increased. It indicates that under 200 mmol/L NaCl treatment, when different concentrations of exogenous melatonin are applied to Potentilla anserine L. seedlings, their various growth and physiological indexes overall present the phenomenon of "low promotion and high inhibition". Under salt stress, applying low concentrations of exogenous melatonin can effectively alleviate the damage caused by salt stress to Potentilla anserine L. seedlings, among which 25 μmol/L has the best effect.