Phase structure and molecular structure of Poly (etheneco-vinyl acetate-g-vinyl chloride) (EVA-g—VC) have been studied in this paper EVA-g-VC consists of free EVA．PVC homopoly-met and EVA-VC copolymer，in which EVA exists as a continuous phase and PVC particles disperse．The size of PVC particles and the grafting efficiency of EVA all depend on the feed-ing ratio-VC／EVA (wt／wt) of a graft polymerization．With decreasing the feeding ratio in the graft gel，the Tg of EVA increases，while the molecular weight and PVC content all decrease．One explanation for this could be suggested that the number of VC grafting points in EVA-VC increases with decreasing the feeding ratio．EVA-VC as an adhesion agent exists between two incompatible phases-EVA(-14) and PVC，which makes the Tg(EVA) and the Tg (PVC) near to another．