The diethylenetriamine (DETA)/polyacrylonitrile (PAN) composite nanofibers were prepared by using electrospirming technique. The surface morphology and chemical characterization of PAN/DETA composite nanofibers were investigated using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Releasing possibility of DETA from nanofibers was tested by total organic carbon (TOC) analysis. Results indicated that the incorporation of DETA into PAN affects the morphology of nanofibers. In order to hinder DETA releasing, this compound was fixed to the polyther using alkali treatment. The obtained PAN/DETA composite nanofibers were evaluated for adsorption of C.I direct red 80 (DR80). The amount of the dye adsorbed onto the PAN/DETA nanofiber mats was influenced by the initial pH, DETA amount, contact time, and the initial concentration of the dye solutions. The maximal adsorption capacity of the dye on the PAN/DETA nanofiber mats was calculated from the Langmuir model.