Abstract: Traditional polyasparthydrazide (PAHy) hydrogel suffers from the problem of low adsorption efficiency due to its poor mechanical properties and low specific surface area. In this study, coaxial electrospinning technology combined with post-modification processes was employed to prepare PAHy/PU hydrogel nanofiber composite membranes. PAHy was used as the functional skin layer and mechanically robust polyurethane (PU) as the supporting core layer. PAHy/PU hydrogel nanofiber composite membranes were used for the separation of dyes by filtration method. The fundamental physicochemical properties of PAHy/PU hydrogel nanofiber composite membranes with different PU core-layer ratios were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), swelling tests, and tensile experiments. The incorporation of the PU core layer effectively enhanced the mechanical properties of the nanofibers. Filtration and separation experiments were conducted to investigate the effects of core-layer composition, solution pH, initial Congo red concentration, and filtration cycles on the adsorption of Congo red by the PAHy/PU hydrogel nanofiber composite membranes, as well as their reusability. The results demonstrated that the composite membranes exhibited optimal filtration and separation performance for Congo red at pH=7, achieving a maximum filtration adsorption capacity of up to 3217.4 mg/g. Filtration-adsorption and desorption cycling experiments indicated that the PAHy/PU hydrogel nanofiber composite membranes possess excellent regeneration performance, maintaining filtration efficiency close to the initial level even after four cycles.