Abstract: To improve the ion conductivity and tensile strength of gel polymer electrolyte (GPE), a novel star-shaped polyhedral oligomericsilsesquioxane-polymethyl methacrylate (POSS-PMMA₈) was successfully synthetized and introduced to the polymethyl methacrylate/polyacrylonitrile/polyvinylidene fluoride (PMMA-PAN-PVDF) matrix to obtain fibrous membrane M1 (POSS-PMMA₈/PMMA-PAN-PVDF) by electrospinning. Membrane M1 was annealed at 120 ℃ to get membrane M2, or processed by hotpressing and pre-oxidizing to get membrane M3. Then the corresponding activated GPEs were prepared by soaking M1, M2 and M3 in liquid electrolyte. The morphologies, porosity, electrolyte uptake, and mechanical properties of these membranes (M1, M2 and M3), as well as the ion conductivity and electrochemical stability of their corresponding GPEs were fully investigated. The results show that, compared to M1, the tensile strength of M2 and ion conductivity of its GPE increase by 9.2% and 181.1%, respectively, and the electrochemical window of M2 and its GPE increases to 5.3 V; besides, the tensile strength of M3 and ion conductivity of its GPE increase by 193.7% and 20.2%, respectively, and the electrochemical window of M3 and its GPE increases to 5.5 V.