The in situ cross-linked PVA/PCM composite nanofibers were prepared by an emulsion-electrospinning process, in which glutaraldehyde (GA) takes a crosslinking reaction with PCM emulsion-PVA blends to form spinning solution confirmed by FTIR. The cross-linked PVA/PCM nanofibers with a core-sheath structure display good thermal energy storage property and thermal stability characterized by TEM, FESEM, DSC and TG. More importantly, compared to PVA/PCM nanofibers, the tensile strength and water resistance of the crosslinked PVA/PCM nanofibers have marked improvments due to a combination of increased crosslinking network structure and decrease in the number of hydroxyl groups on the surface of nanofibers, which greatly expand the potential application field of PCM nanofibers.