A　novel　superabsorbent　was　prepared　by　utilizing　carboxymethyl　starch　and　carboxymethyl　cellulose　biocomposites　as　a　grafting　backbone.　The　scheme　of　the　CMS-CMC　double　backbone　structure　was　speculated.　It　was　proposed　that　the　superabsorbent　possesses　a　three-dimensional　network　with　an　interpenetrating　structure.　The　response　surface　methodology　was　used　to　optimize　the　parameters.　Interactions　among　the　most　influential　variables,　i.e.,　the　dosage　of　CMC,　the　acrylic　acid　to　acrylamide　mass　ratio,　and　the　neutralization　degree　of　acrylic　acid　were　estimated.　A　mathematical　model　was　developed,　which　fit　the　experimental　results　well　for　all　of　the　response　variables.　The　optimal　conditions　included　28.8　%　of　CMC　dosage,　a　1.6　mass　ratio　of　acrylic　acid　to　acrylamide,　and　73.4　%　of　neutralization　degree　of　acrylic　acid　to　achieve　815.2　g/g　of　water　absorbency.