As the typical brown alage,Sargassum fulvellum contains a large amount of the carbohydrate,it can be used to produce bioethanol after pretreatment.The overall goal of this work was to develop a saccharification method for the production of bioethanol using Sargassum fulvellum.A two-step hydrolysis method including acid hydrolysis(first stage) and enzyme hydrolysis(second stage) was carried out to optimize the condition for the saccharification of sargassum.Results displayed that the acid hydrolysis efficiency of first stage was 31.05%±0.32%(w/w dry biomass) of the reducing sugar under optimum conditions of feed content 6%(w/v),1.5%(v/v) sulfuric acid,120℃ and 40min.After enzyme hydrolysis of second stage,the efficiency of the saccharification was increased by 9.68% under optimum conditions of feed content 5%(w/v),alginate lyase concentration 0.0025%(w/v) and reaction time 2h.The reducing sugar yields from Sargassum fulvellum using a two-stage hydrolysis method was 38%~40%(w/w dry biomass),which reached 89% of the theoretical yields.The hydrolyzate derived from Sargassum fulvellum by a two-stage hydrolysis was employed for conversion to ethanol by industrial Saccharomyces cerevisiae R1-11.The highest ethanol yield was 91.9 g/kg dry biomass.