A novel amidoximated polyacrylonitrile nanofibrous membrane (AO-PAN NFM) is synthesized by post-amidoximation of PAN NFM prepared via simultaneously biaxial stretching for the first time. With layered stack structure consisting of cross-linked nanofibers, the AO-PAN NFM is characterized by high specific surface area and outstanding hydrophilicity. Accordingly, it exhibits high uranium adsorption capacity, excellent selectivity, outstanding reusability with fast and efficient desorption response. Meanwhile, the chemical adsorption dominates the uranium adsorption behavior of AO-PAN NFM. Notably, compared with electrospinning and blow spinning processes, the simultaneously biaxial stretching method has unique advantages, such as membrane thickness control, good mechanical properties and high productivity of large-scalable production etc. The novel AO-PAN NFM produced by the new stretching method shows great application potential as a new strategy for uranium extraction from seawater to support future nuclear energy generation.