Nanofiber films froms different proportion of konjac glucomannan (KGM)/poly(vinyl alcohol) (PVA) have been synthesized using electrospinning and used for sustained drug release. KGM was crosslinked with PVA to form a composite liquid, which was used as spinning solution to prepare KGM-PVA film by electrospinning. The drug release behavior of KGM-PVA nanofiber membrane was studied using 5-ASA as model drug. The microstructure of the composite nanofiber films was characterized by scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR), while the thermal properties were analyzed by differential scanning calorimeter (DSC). The sustained-release of the model drug from the nanofiber films was studied in vitro and with a mathematical model of drug release. It was observed that a uniform nanofiber with no node was synthesized when about 76% of KGM in the nanofibers film was used. Under this condition, thermal stability was enhanced as well. The structure characterization illustrated that the nanofiber membrane of the composite KGM-PVA was formed by stacking of the numerous nanofibers. Intermolecular reaction between KGM and PVA led to an enormous change in the structure and the function of the composite films in comparison with other KGM derived films. A relatively large specific surface area was formed during the formation of the network structure in the nanofiber film, which favored drug adsorption. The in vitro experiment results revealed that nanofiber film containing 5-aminosalicylic acid in PBS buffer of pH = 7.4, performed well sustained-release and the cumulative release rate was about 45% after 25 h. The results also showed sustained-release from the nanofiber films was better fitted with Higuchi model. This study indicated that KGM/PVA nanofiber film developed by electro spinning provided a theoretical base for the development of the carrier for sustainable drug-release.