NOVELTY - The membrane comprises a mixed layer arranged with a three-dimensional (3D) network structure supporter and an ion migration domain. The mixed layer comprises first ion conductor polymer. Ion exchange capacity (IEC) of the first ion conductor polymer is 1.7-2.5 meq/g. A pure water layer is laminated in an upper side of the mixed layer. The pure water layer comprises second ion conducting polymer. IEC of the second ion conducting polymer is lower than that of the first ion conductor polymer. Thickness of the mixed layer is 1-30micrometers. Thickness of the pure water layer is 6micrometers.    USE - Polymer electrolyte membrane for use in a membrane electrode assembly of a fuel cell (all claimed) e.g. alkaline fuel cell (AFC), phosphoric acid fuel cell (PAFC), thermal electric cell structure of fusing carbonate (MCFC), solid oxide fuel cell (SOFC), polymer electrolyte fuel cell (PEMFC) and direct methanol fuel cell (DMFC), that is utilized in a portable power source, a vehicle and a portable apparatus at a home and an electricity industry.    ADVANTAGE - The mixed layer is arranged with the 3D network structure supporter and the ion migration domain, and the mixed layer comprises the first ion conductor polymer so as to facilitate repetitive contraction and expansion of the membrane without any deformation, so that ion conductivity, durability and operating performance of the membrane can be improved and high-temperature humidification and drying phenomenon occurrence about the membrane can be avoided.    DETAILED DESCRIPTION - The 3D network structure supporter comprises hydrocarbons, fluoride group material, semi-crystalline polymer, polyolefin, fluorocarbon, polyamide, polyester, polyacetal, polysulfide and polyvinyl alcohol. The first and second ion conductor polymers are sulfonation fluoropolymer, sulfonation benzimidazole group polymer, sulfonation polyimide-based polymer, sulfonation polyetherimide group polymer, sulfonation polyphenylenesulfide group polymer, sulfonated polysulfone polymer, sulfonal polyether sulfone polymer, sulfonated polyetherketon polymer, sulfonation polyether-ether ketone polymer, sulfonation polyphenyl quinoxalin class polymer or sulfonation part fluoride group material.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a polymer electrolyte membrane.