Abstract: In order to optimize the conditions of ultrasonic-assisted extraction method of polysaccharides from Rhodiola dumulosa (Franch.) S.H.F., on the base of single-factor experiment, an equation for the ultrasonic wave extraction was built. The experimence showed that extraction temperature, ultrasonic power, extraction time and liquid-solid ratio had different effects on the extraction yield of polysaccharides. The result indicated that within tested level ranges, the importance of four process parameters affecting extraction yield of polysaccharides order was ultrasonic treatment temperature, ultrasonic power, solid-liquid ratio and ultrasonic treatment time. The optimum conditions of the ultrasonic wave extraction of R. dumulosa polysaccharides were as follows:temperature 69℃, extraction ultrasonic power 240W, solid-liquid ratio 1∶30 (g/mL) and extraction time 39min, the extraction rate of R. dumulosa polysaccharides could be up to 4.305%, exhibiting a good agreement with the predicted values.