The technology of extracting polysaccharide from Leucaena leucocephala was optimized by single factor experiment and orthogonal experiment L9(33). The result showed that the order of main factor effecting the extracting rate was extracting time, the ratio of material with liquid and extracting temperature. The optimal conditions were as followed: extracting temperature 60℃, extracting time 5h, the ratio of material with liquid 1∶35 and the concentration of alcohol 95%vol. Under these conditions, the extraction yield can be up to 12.16%. No nuclear-acid and protein were found in the polysaccharides by ultraviolet detection and ninhydrin reaction.