Abstract: The Nylon 6 (PA6)/Polyvinylidene fluoride (PVDF)/Nylon 6 (PA6) three-layer composite membrane with a sandwich structure for gel polymer electrolyte is prepared by continuous electrospinning. Scanning electron microscopy (SEM) showed that the membrane is composed of disordered nanofibers interwoven with each other, with a large number of interpenetrating 3D channels. The thermal stability of the diaphragm is analyzed with differential scanning calorimetry (DSC). The special porous sandwich structure and the combination of the two materials can effectively improve the safety of the lithium ion battery. Gel polymer electrolyte (GPE) is obtained by absorbing a small amount of lithium hexafluorophosphate electrolyte (1 mol/L LiPF₆ solution, ethylene carbonate(EC)/dimethyl carbonate(DMC)/ethyl methyl carbonate(EMC), 1∶1∶1 for mass ratio) with a composite membrane. The ionic conductivity of the electrolyte reaches 4.2 mS/cm at room temperature, and the interfacial dynamic stability between the electrolyte and the electrode is good. In order to study the practicability of gel polymer electrolyte, a button battery is assembled with lithium sheet anode and commercial lithium iron phosphate cathode material. The battery shows good cycling and rate performance.