Abstract: Objective: To optimize conditions for the extraction of polysaccharides from longan seeds. Methods: Based on single factor experiments, the optimal conditions for polysaccharide extraction were explored by Box-Behnken design (BBD) in combination with response surface methodology (RSM). Results: The optimal extraction conditions of polysaccharides were ethanol concentration of 70% (V/V), extraction temperature of 77.4 ℃, extraction time of 4 h, solid-to-liquid ratio of 1:20 (g/mL) and extraction number of 2. Temperature was the most important affecting factor of polysaccharide extraction, followed by extraction time and ethanol concentration. Under such extraction conditions, the experimental yield of polysaccharides obtained after the first extraction was up to 21.7079 mg/g, which was close to the model-predicted value. Conclusion: The established regression equation for polysaccharide yield has an excellent goodness of fit. Therefore it is credible and can be used for practical prediction

Key words: longan seed, polysaccharides, response surface methodology