The morphological structures and the related thermophysical propeRies of the complex differential of polyethylene oxide and lanthanide salts (Ln3+) were investigated by polarized optical microscope (POM) and differential scanning calorimeter (DSC)．The results showed that with the increase of molar ratio of Ln3+ salts to PEO,PEO spherulites were gradually demolished．When the molar ratio reached a critical value,for example,20,PEO spherulites completely disappeared．Different Ln3+ salts have different effect on PEO spherulites．The results of X-ray diffraction indicated the decrease of main peaks at 2θ=19.2° and 23.4° with the increase of Eu3+ salt concentration,which coincided with the data of DSC and POM．The characteristic of spherulites of complex samples was much weaker after vacuum drying at 600C than that at 23℃ in fume hood．Comparing the spherical structure of the original cast-drying sample,we found that the complex between PEO and Eu3+ remaimed after the first cooling． The melting point and heat of fusion of PEO decrease with the increase of Ln3+ concentration．When the concentration reached the related critical values,melting endotherms disappeared and melting points of PEO Were down to the lowest values．The change of FT-IR band at 1036 cm-1 confirmed the complex characteristic of the interaetion between PEO and Ln3+ salts.