Abstract: Polymethylmethacrylate (PMMA)/lithium ethylene-vinyl alcohol copolymer sulfate (EVOH-SO₃Li) Li-ion battery separator composite was prepared by means of electrostatic spinning alternated, PMMA and EVOH-SO₃Li as raw materials. The performance of PMMA/EVOH-SO₃Li separator composite was characterized by FTIR, SEM, universal tensile tester, TGA, IM6 electrochemical workstation and battery cycler. The results show that PMMA/EVOH-SO₃Li separator composite has a clear three-dimensional network structure. Compared with EVOH-SO₃Li separator, the porosity, absorption rate and tensile strength of modified PMMA/EVOH-SO₃Li separator composite are increased to 80%, 340% and 3.18 MPa, respectively. The initial thermal decomposition temperature is also rised to 294℃. The thermal shrinkage rate is reduced. The excellent electrochemical performance is exhibited. The electrochemical stability window is increased from 5.0 V to 5.6 V. The interfacial impedance is reduced from 420.69 Ω to 262.31 Ω. The ionic conductivity is increased from 1.560×10^-3 S/cm to 2.089×10^-3 S/cm. The coulombic efficiency is 93.7% after 100 cycles of charge and discharge.