In electrospinning, non-woven fabrics are commonly used as substrates to receive polymer nanofibers. Nanofiber mats formed in this process have many advantages, such as extensive application prospects in the thermal insulation, filtration, protection and so on. Polyvinyl alcohol (PVA) is the main electrospun material with excellent physical properties, biodegradable properties, chemical resistance, and good mechanical properties in the dry state. However, PVA has a poor water resistance which limits its application. In this study, The PVA nanofibrous mats prepared by electrospinning were chemically crosslinked with glutaraldehyde (GA) in acetone. Scanning Electron Micrograph (SEM) and Fourier Transform Infrared (FTIR) spectrometry were employed to characterize the morphology and structure of crosslinked PVA nanofiber mat and PVA nanofiber mat. The differences of morphology and structure between the modified and nonmodified nanofiber mat were revealed. Such nanofibrous mat has good water resistance and excellent warmth retention property. Thus, the practical applications of PVA nanofiber mats were broadened.