The objective of this work is to demonstrate the feasibility of preparation of core-shell nanofibers byelectrospinning combined with in situ UV photopolymerization. The thiol-ene monomer with Si atomand the initiator can migrate to the surface with the evaporation of the solvent during the process ofelectrospinning, which caused phase separation due to the great migration ability of small molecule andlow surface energy. Then photo induced polymerization and cross-linking reaction took placesimultaneously during the electrospinning process, which formed shell of the nanofibers. Themorphology and structure of electrospun nanofibers were investigated by SEM and TEM. Thecomposition of the shell layer was determined by ATR-IR and XPS. Moreover, the nanofiber mats weretested by WCA test, and the hydrophobic ability of PVP nanofibers was improved because of theprotection of the shell layer with Si atom. The most important thing is that the technology whichcombined electrospinning with in situ photopolymerization provides a simple method for preparation ofcore-shell nanofibers.