The acrylonitrile (AN)–methoxy polyethylene glycol (350) monoacrylate (MPGA)–lithium acrylate (LiAc) copolymers (PAMGLiAc) was synthesized by emulsion polymerization. Phase inversion technique was used to prepare the PAMGLiAc microporous membrane. The gel polymer electrolytes (GPEs) with the PAMGLiAc were obtained by the copolymer microporous membrane soaking liquid electrolyte. The component and structure of the PAMGLiAc were characterized by IR, NMR and TGA/DSC measurement. The electrochemical characteristics of the PAMGLiAc gel electrolytes were investigated in terms of different composition. The ionic conductivity exceeded 2.0×10−3 S/cm at ambient temperature, and this system also showed good mechanical properties and a sufficient electrochemical stability with a decomposition voltage as much as 5V vs. Li to allow far wider operation in the rechargeable lithium-ion polymer batteries.