Abstract: Appropriate concentration and physiological characteristics of exogenous melatonin to mitigate cadmium stress in corn was investigated, addressing problems that cadmium pollution inhibits corn growth and underlying exogenous melatonin mitigation mechanism remains unclear, to provide a basis for corn safe production in cadmium-contaminated fields．Zhengdan 958 corn was treated as material．Control groups were set as no cadmium and no melatonin（CK₁）, and 100 mg/L Cr⁶⁺ stress control（CK₂）．100 mg/L Cr⁶⁺was added at concentrations of 10, 50, 100, and 200 μmol/L exogenous melatonin as treatment groups（T₁ to T₄）．Seed germination, seedling growth, photosynthetic pigments, antioxidant enzymes, osmotic regulatory substances, and cadmium absorption transport indicators were measured．Results indicated that when exogenous melatonin was applied at a concentration of 50 μmol/L, it achieved the best mitigation effect against cadmium coercion．Compared with sole chromium stress treatment, corn seed germination rate and vitality index increased by 44.77% and 115.56%, respectively．While chlorophyll a and chlorophyll b content in seedlings increased by 57.14% and 68.29%．respectively．Enzyme activities of superoxide dismutase（SOD）, hydrogen peroxide（CAT）, and peroxidase（POD）increased by 58.68%, 56.00% and 59.12%, respectively．It regulated osmotic regulatory substances metabolism such as proline and soluble sugars, reducing chromium absorption and transport in seedlings．Cadmium content in roost and shoot decreased by 50.12% and 57.90%, respectively．These findings indicated that 50 μmol/L exogenous melatonin effectively mitigated cadmium stress inhibiting effects on corn．This mitigation occurred by protecting photosynthetic properties, enhancing antioxidant capacity, regulating osmotic metabolism, and inhibiting cadmium absorption and transport．