For a long lime, the fragility of ceramic nanofibers is a key issue for their application in wearable nano devices. BaTiO3 (BTO) flexible nanofibers with excellent elastic modulus of 1.33 GPa and high morphology integrity have been successfully obtained by electrospinning. The BTO flexible nanofibers with diameter around 100 nm have pure perovskite structure at room temperature and no secondary phase. Further analysis shows the prepared BTO flexible nanofibers to have core-shell structure, which are thought to be responsible to its improved elastic response. In addition, the comparative experiments show the oxygen vacancies to play an important role in the formation of core-shell structure. This work provides an effective approach for designing advanced mechanical properties of BTO nanofibers. The BTO nanofibers after being calcined in nitrogen atmosphere show better surface morphology and crystallinity than the nanofibers calcined in other atmospheres. The results reveal that the nitrogen atmosphere will effectively modify the mechanical properties of the BTO nanofibers.