Abstract: Under the stress of 15 mg·kg⁻¹ Cd, the effects of single and combined treatments of 75 mg N·kg⁻¹ nitrogen fertilizer（\rm N\mathrmO_3^-\text-\mathrmN ） and 1 mmol·L⁻¹ s,s -ethylenediaminedisuccinic acid（EDDS）on physiology, biochemistry and active oxygen metabolism of Solanum nigrum seedlings were investigated by pot experiment. The results indicated that under the condition of Cd stress, \rm N\mathrmO_3^-\text-\mathrmN （Cd+N） or EDDS single treatment （Cd+EDDS） significantly increased the photosynthetic pigment and some antioxidant enzyme activities and antioxidant content of S. nigrum compared with Cd treatment, and alleviated the stress of Cd on S. nigrum. The combined treatment of \rm N\mathrmO_3^-\text-\mathrmN and EDDS （Cd+N+EDDS） can further effectively improve the resistance of S. nigrum to Cd: Compared with Cd treatment, Cd+N+EDDS treatment significantly promoted the biomass of S. nigrum, while the plant height, root length, total fresh weight and dry weight increased by 20.29 %, 22.34 %, 19.50 % and 28.56 %, respectively; Compared with Cd treatment, Cd+N+EDDS treatment made the activity of peroxidase（POD）, catalase（CAT）and content of soluble protein（SP） reach the maximum, which increased by 80.05 %, 88.66 % and 28.09 % respectively. Comprehensive analysis showed that under the stress of 15 mg·kg⁻¹ Cd, Cd+N+EDDS treatment could effectively promote the growth of S. nigrum. It could also increase the content of antioxidant substances, thereby mitigating the membrane lipid peroxidation damage of S. nigrum and enhancing its resistance to Cd.