CMC/PVA composite nanofiber membrane was prepared by electrostatic spinning method, using carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA) as raw materials and glutaraldehyde as cross-linking agent. The structure, morphology, thermal stability, and filtration performance of CMC/PVA nanofiber membranes were characterized by advanced instrumental analysis methods such as scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet analysis and energy spectrum analysis. The results show that the average fiber diameter decreases from 381 nm to 183 nm, when the spinning voltage is 23 KV and the jet speed is 2 µL/min. The obtained fiber has the smallest particle size and the most uniform distribution. Infrared spectroscopy analysis confirms that the adsorption behavior of nanofiber membranes on Cu2+ and Cr6+ is chemical adsorption. The retention rates of CMC/PVA nanofiber membranes for Cu2+ and Cr6+ reached 97% and 98%, respectively.