Crosslinked PVA fibers were found be efficiently crosslinked by maleic anhydride (MAH). Vitriolic acid (H2SO4) was used as a catalyst during crosslinking. Scanning electron microscopy (SEM) and infrared reflection-absorption spectroscopy (FTIR) were employed to characterize the morphology and crosslinking of PVA fibers. Compared with PVA nanofibers and PVA powder, some characteristic bands of -C=O -C=C-, C-O-C and COOH of crosslinked PVA nanofibers are distinct in the infrared spectrum. Moreover, the filtration properties of crosslinked PVA nanofibers were tested.