Polyethylene (PE)-supported poly(methyl methacrylate-vinyl acetate)-co-poly(ethylene glycol) diacrylate with and without doping nano-Al2O3, namely P(MMA-VAc)-co-PEGDA/PE and P(MMA-VAc)-co-PEGDA/Al2O3/PE, are prepared and their performances as gel polymer electrolytes (GPEs) for lithium ion battery are studied by mechanical test, scanning electron microscopy, thermogravimetric analyzer, electrochemical impedance spectroscopy, cyclic voltammetry, and charge/discharge test. It is found that the doping of nano-Al2O3 in the P(MMA-VAc)-co-PEGDA/PE improves the comprehensive performances of the GPE and thus the rate performance and cyclic stability of the battery. With doping nano-Al2O3, the mechanical and thermal stability of the polymer and the ionic conductivity of the corresponding GPE increases slightly, while the battery exhibits better cyclic stability. The mechanical strength and the decomposition temperature of the polymer increase from 15.9MPa to 16.2MPa and from 410°C to 420°C, respectively. The ionic conductivity of the GPE is from 3.4×10−3 Scm−1 to 3.8×10−3 Scm−1. The discharge capacity of the battery using the GPE with doping nano-Al2O3 keeps 90.9% of its initial capacity after 100 cycles and shows good C-rate performance.