The action mode between Dy(III)(NR)₃ and herring sperm DNA is studied by ultraviolet-visible (UV-vis) and fluorescence spectra as well as electrochemistry. Double-reciprocal method studies show that the binding stoichiometry between Dy(III)(NR)₃ and DNA is 1:1, the binding constants at different temperatures are 1。15×10⁵ L/mol at 25 ℃ and 2.09×10⁵ L/mol at 35 ℃, and the corresponding thermodynamic parameters are \Delta_rH \mathrm m = 2.48×10⁴ J/mol, \Delta_rG \mathrm m =-2.34×10⁴ J/mol, \Delta_rSm=161.7 J/(mol·K); \Delta_rS \mathrm m is the driving force in this reaction. Combined with Scatchard method and melting method, the results suggest that the interaction mode between Dy(III)(NR)₃ and herring sperm DNA is intercalation fashion and groove fashion.