Poly(vinyl chloride) (PVC) with pendent N,N-diethyldifhiocarbamate groups (PVC-SR) was prepared through the reaction of PVC with sodium N,N-diethyldithiocarbamate (NaSR) in butanone and used as a photoinitiator for the grafting polymerization of three vinyl monomers [styrene (St), methyl methacrylate (MMA), and acrylamide (Am)]. The effects of ultraviolet (UV) irradiation time, PVC-SR amount, and the monomer amount on grafting and grafting efficiency were investigated. The results showed that PVC-SR could initiate the polymerization of three vinyl monomers effectively and obtained crosslinked copolymers. The grafting and grafting efficiency of styrene and methyl methacrylate were higher than those of acrylamide. The polymerization activity of three monomers was acrylamide > methyl methacrylate > styrene. By analyzing the UV spectrum of PVC-SR with a different irradiation time, it was confirmed that PVC-SR was dissociated mainly into macromolecular the sulfur radical PVC-S and the small molecular carbon radical C(S)N(C2H5)(2); the grafting polymerization mechanism was discussed.