Ionizing radiation directly causes serious damage to human health, and a protective system capable of absorbing or reflecting ionizing radiation is required urgently. In this work, electrospun poly(vinyl alcohol) (PVA) and Poly(vinyl Alcohol)/Erbium Oxide (PVA/Er2O3) nanocomposite fibrous mats were fabricated. These PVA or PVA/Er2O3 composite nanofibers were completely characterized using scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Furthemore, air permeability and ionizing radiation protection properties of these mats were also measured. Under a certain constant electropinning condition, the PVA or PVA/Er2O3 composite nanofibers showed an excellent morphology. The ionizing radiation protection capability of nanofibrous mats is considerably improved when incorporated with Er2O3 nanoparticles.