Aims Many studies have proved that EDTA (ethylenediaminetetraacetic acid), EDDS ([S, S']-ethylenediamine disuccinic acid), and other chelating agents significantly enhance phyto-extraction of copper (Cu) from soil. However, some key factors, such as changes in membrane permeability of root cells and subcellular distribution of Cu and Cu-EDDS complex in leaves and roots, remain unresolved. Methods A pot-culture experiment was conducted using soil artificially contaminated with Cu to different degrees to compare its effect on the above factors and the relationship between them in maize (Zea mays L.). Results Treatment with 0.5-6.0 mmol kg −1 (soil) EDDS increased membrane permeability in root cells significantly (p<0.05). Chelated Cu accounted for 14.6%-17.4% of the total Cu content of roots and 77.7%-78.8% of that of leaves and was distributed mainly in cell walls in both.Conclusions EDDS increases Cu accumulation in shoots mainly by increasing the content of soluble Cu in soil and membrane permeability of root cells. Cu in soil may be absorbed through the apoplastic pathway into the root xylem, translocated to the shoots, and accumulated there as a Cu-EDDS complex.