A　supercritical　water　pretreatment　was　applied　to　cellulose　dissolution　and　hydrolysis.　The　effects　of　temperature,　residence　time,　and　ratio　of　solid/liquid　phase　on　the　cellulose　dissolution　and　sugar　conversion　were　investigated.　The　results　showed　that　cellulose　could　dissolve　completely　in　a　short　time　at　380　degrees　C　and　higher　temperature.　The　reaction　temperature　has　significant　effect　on　consequent　hydrolyzation　and　sugar　conversion　in　the　range　of　374　similar　to　386　degrees　C,　and　the　highest　concentration　of　oligosaccharides　and　hexoses　was　obtained　around　the　critical　point.　On　the　other　hand,　these　products　were　also　decomposed　rapidly　under　the　supercritical　condition　with　the　extending　of　reaction　time.　The　ratio　of　initial　solid/liquid　phase　affects　the　cellulose　hydrolyzation　markedly　as　well.　The　best　results　were　obtained　with　40　mg　cellulose/2.5　mL　water　at　380　degrees　C　and　16　s,　affording　oligosaccharide　recovery　above　29%,　or　80　mg　cellulose/2.5　mL　water　at　380　degrees　C　and　18　s,　affording　hexose　recovery　above　39%.