The interaction of complex Eu(bpy)_3 (3+) with DNA was studied by fluorophotometry. The binding constant ( K ) and size ( n ) of the binding site were calculated according to the changes of the fluorescent intensity at the adding process of DNA. The model for the complex Eu(bpy)_3 (3+) interacted with DNA solution is found to be electrostatic action. The system Eu(bpy)_3 (3+)-DNA was studied by the voltammetry. The interaction of the complex Eu(bpy)_3 (3+) with the calf thymus DNA was investigated by fluorophotometry,then K and n were obtained. The interaction of complex Eu (bpy) _3 (3+) with DNA was studied by fluorophotometry. The binding constant (K) and size (n) of the binding site were calculated according to the changes of the fluorescent intensity at the adding process of DNA. The model for the complex Eu (bpy) _3 (3+) interacted with DNA solution is found to be electrostatic action. The system of Eu (bpy) _3 (3 +) - DNA was studied by the voltammetry. The interaction of the complex Eu (bpy) _3 (3+) with the calf thymus DNA was investigated by fluorophotometry, then K and n were obtained.