Taking drying powder of Artemisia argyi Lévl. et Vant. leaves as materials, single factor experiments about ultrasonic treatment time, solid-liquid ratio ( mass-volume ratio), water bath temperature and extraction time which may affect on polysaccharide extraction rate were detected. And on this basis, four factors were optimized by L₉(3⁴ ) orthogonal experiment design. The results show that according to influence on extraction rate of polysaccharide, the order of four factors from high to low is extraction time, solid-liquid ratio, ultrasonic treatment time, water bath temperature. The optimal extraction condition is solid-liquid ratio 1︰40, ultrasonic treatment time 20 min, water bath temperature 80 ℃, extraction time 2. 0 h. Under the optimal condition, the extraction rate of polysaccharide from A. argyi leaves is the highest with a value of 12. 2% .