Abstract: Novel acetoacetic ester-terminated polyether was synthesized by the reaction between polyether and diketene. The products were characterized by FT-IR、1H-NMR and 13C-NMR. Results show that acetoacetic ester-terminated polyether has an enol form tautomer and the tautomer is stable. This new kind of acetoacetic ester-terminated polyether can be used for the synthesis of polyether- imine elastomer which has good mechanical property.