Abstract: In order to make the best use of seaweed resources,compound enzymes method(including hydrolase and cellulase)was used in this research to extract sodium alginate from Sargassum horneri. Based on the single factor experiment of enzyme concentration,temperature,pH and time,the orthogonal experiment was used to optimize the extraction process. Results showed that the optimal conditions were hydrolase concentration 0.8%,the cellulase Ⅱ concentration 1%,enzymatic hydrolysis under the condition of 55℃ and pH5 for 90 min. After alkali digestion decolorization,calcium agglomerating,acidification and alcohol precipitation,the yield rate of sodium alginate could reach to 24.51%±0.54%,which was 46.70% higher than traditional method(16.71%). The compound enzymes method could provided an effective technical way for the value-increment utilization of S. horneri. Microscopic observation by SEM showed that enzymatic hydrolysis could effectively destroy the structure of cell wall,promote the dissolution of polysaccharides and improve the extraction rate of sodium alginate. Compared with the traditional method,the new output of enzymes method was much higher than the cost of multi-consumption,while the enzymes method reduced the amount of dilution water and industrial wastewater. Extraction of sodium alginate by enzymes method provide an effective technical way for the value-increment of S. horneri and it had extensive application prospect.