This paper deals with the graft copolymerization of viscose fiber-styrene in suspension. It was found that by the addition of a suitable amount of sulfur as inhibitor a definite induction period for homopolymerization can be induced. Within this induction period the graft copolymerization can proceed to completion and thus fully eliminate the formation of homopolymers. The addition of proper amount of inhibitor does not affect the rate of graft copolymerization and the unreacted monomer can be recoverd.