The complexation and the electrochemical behavior of Eu2+ and Eu3+ in poly (ethylene glycol) (PEG) oligomers were studied．Eu3一PEG complexes were pre-pared by dissolving EuCl3 into PEG with various molar masses．They showed strong excitation and emmision bands at 394 and 614nnl，respectively．The intensi-ties of both bands increased with the increase in PEG molar mass．Eu2+一PEG complexes were formed by the reduction of corresponding EuCl3 solutions at一2.0V (VS Ag) and under N2，by using indium／tin oxide (ITO) coated glass sheet as working electrode．Their luminescence properties very like that of the complex formed by Eu2+ and 18-C-6 crown ether (ex. =326—328 nm，em．=440—1445nm)，which demonstrated that the chemical environment of PEG was very similar to that of large ring poly—oxygen ligand．The redox process of trivalent europium in PEG is very irreversible，and its behavior could be strongly affected by adding supporting electrolytes．The complexation and the electrochemical behavior of Eu2+ and Eu3+ in poly (ethylene glycol) were studied by using IR，fluorescent spectroscopies and cyclic voltammetry．