A novel water swellable rubber (WSR) was prepared by blending chlorohydrin rubber (CHR) with crosslinked polyacrylate (CPA), poly(vinyl alcohol)-g-poly(butyl acrylate) (PVA-g-PBA), precipitated silica (PSA), and poly(ethylene glycol) (PEG). The amphiphilic graft copolymer PVA-g-PBA was incorporated as the compatibilizer between CHR and CPA. Water swellable-rubber With different grafting percentages and contents of PVA-g-PBA was investigated by SEM, mechanical measurement, and water-swelling tests. The results prove that. PVA-g-PBA increased interfacial cohesion between CHR and CPA before and after water swelling, decreased percentage loss by weight, and improved water-swelling behavior. Mechanical properties of WSR were significantly improved by PVA-g-PBA, especially for the blends of 5 phr PVA-9-PBA with G% = 151.7% before water swelling and that with G% = 340.4% after water swelling.