Abstract: The purpose of this study was to optimize the extraction of polysaccharides from the fruits of Sorbus tianschanica Rupr.. Polysaccharide contents of different parts of Sorbus tianschanica Rupr. including roots, stems, leaves and fruits were assayed spectrometrically, followed by optimizing conditions for the extraction of polysaccharides from the fruits of Sorbus tianschanica Rupr. by orthogonal array design method. The fruits of the plant showed the highest polysaccharide content (4.63%) among the four parts. The optimized extraction conditions were using distilled water as the extraction solvent at a material/liquid ratio of 1:45 for 45 min extraction with the assistance of 240 W ultrasonic treatment. Under these conditions, the highest extraction yield of polysaccharides from the fruits of Sorbus tianschanica Rupr. could reach 5.92%. Moreover, material/liquid ratio was found to be the most significant factor affecting polysaccharide extraction.

Key words: Sorbus tianschanica Rupr., polysaccharide, extraction technology