The core-shell nanofibers containing PDA-PEI co-modified Li0.33La0.57TiO3 (LLTO) perovskite nanowires in the shell layer were fabricated by co-axial electrospinning technique to apply as separator in dendrite-free lithium metal batteries. The PVDF-HFP with good mechanical properties and polar C-F bonds was used as core material, and PAN with high thermal stability was employed as shell layer in nanofibers. The PDA-PEI co-modified Li0.33La0.57TiO3 nanowires, reacting with PF6- anions in LiPF6 salt, can not only capture free anions but also provide a lithium-ion migration pathway. Moreover, the core-shell structured nanofibers exhibited high mechanical strength (9.2 N mm-2), robust thermal stability (> 0% at 200 for 1 h), and favorable electrolyte affinity (electrolyte uptake of 732 %). Gelation of PVDF-HFP in liquid electrolyte leads to high ionic conductivity (3.52 mS cm-1), Li+ transference number (tLi+= 0.68), uniform Li+ flux, and smooth Li deposition. The Li plating/stripping test consisting of Li-Li cells (with CS/LLTO-PDA-PEI) carried out at 0.4 mA cm-2 was conducted for 1000 h without a short circuit. NCM-Li and NCM-Gr coin cells using the CS (core-shell) /LLTO-PDA-PEI separator retained long-term cycle stability and good Coulombic efficiency (CE).