A polymer matrix of poly(acrylonitrile-maleic anhydride) (P(AN-MAH)) is used to prepare a novel porous membranes by phase inversion. The membranes are immersed into liquid electrolyte to form gel polymer electrolyte (GPE) used in lithium ion batteries (LIBs). The results indicate that P(AN-MAH) is successfully synthesized and the membrane of P(AN-MAH) copolymer with adding mass ratios of AN: MAH = 4:1 exhibits superior pore structure and better thermal stability compared with that of pure PAN membrane, which endows the corresponding GPE with excellent comprehensive performances: the considerable ionic conductivity (3.03 × 10−3 S cm−1 at room temperature), fine compatibility between GPE and electrode, eminent lithium transference number (t Li + = 0.57), and high enough electrochemical stability potential (up to 5.4 V (vs. Li/Li+)). Accordingly, in constant current charging/discharging cycle, the prepared battery for the GPE also presents excellent initial discharge capacity, C-rate and cycling performances.