Ethylene-tetrafluoroethylene(ETFE)copolymers are widely used in wire and cable insulation of aircraft and aerospace,construction film and flexible solar membrane.These applications are irreplaceable due to their unique chain structure of ETFE.Based on the molecular structure,the critical techniques in the development of ETFE resins are investigated.The influence of the third monomers both on polymerization process and properties of the resulting ETFE resins are carefully reviewed.The preliminary principles for choicing the third monomer are provided.Meanwhile,the influence of the mole fraction of the tetrafluoroethylene on the properties of ETFE is also discussed.On the other hand,the researchers are troubled in the characterization of the ETFE molecular structure for many years due to the high melting point and insolubility of ETFE.Therefore,the published characterization methods for the molecular structure of ETFE are concluded and discussed.