In this study, the polyacrylonitrile (PAN)-based precursor was produced by electrospinning for the fabrication of oxidized nanofiber nonwovens. The parameters adopted for the oxidation process were chosen from the thermal analysis results obtained using DSC and TGA. The oxidation temperatures of 270, 300, and $330^{circ}C$ were selected for heating times of 30, 50, and 70 min at three levels of tension. The variations in yield rate, breaking strength, shrinkage and stiffness of the oxidized PAN-based electrospun nonwovens were examined in this article. The results indicate that the physical properties of electrospun nonwovens were affected by the oxidation conditions. In addition, the $underline{l}$imit $underline{o}$xygen $underline{i}$ndex (LOI) was found to increase with increasing heat treatment temperature and time. In addition, the optimum oxidation condition was found to be heating temperature of $300^{circ}C$ for a duration of 70 min. Under this condition, high-quality PAN-based oxidized electrospun nonwovens were produced with aromatization index (AI) of 62 % and LOI of 44 %.