N-Substituted polyurethanes were synthesized by the reaction operating in a two-step process, namely, firstly metalation of the starting PEO-based polyurethane (PEOPU) with potassium ter-butoxide and then treatment of the obtained urethane polyanion with tosylate of alkyl or oligo(ethylene oxide) derivatives under the inert gas and at 5 ℃ conditions in dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF) mixing solvent. A series of polyether polyurethanes with differing oligo(ethylene oxide) side chain were synthesized. The chemical structures of the N-substituted PEOPU were confirmed by the FT-IR and 1H-NMR. Mechanical property of the N-substituted PEOPU observed by DMA and UTM.