Abstract: The ultrasonic method was applied to extract of total saponins from snap bean. Regarding the content of total saponins in snap bean as the index of investigation,the factors such as the ultrasonic temperature,ultrasonic powerand,ultrasonic time affecting the content of total saponins were studied. Single and orthogonal tests were performed to optimize the extraction conditions. The optimal conditions are determined just as follows: ultrasonic temperature 50 ℃,ultrasonic power 80%,and ultrasonic time 50 min. The total snap bean saponins content in obtained extract 3.416mg/g. By the common solvent method the content of total saponins is 3.463mg/g.Ultrasonic can not increase the extraction rate of total snap bean saponins remarkably,but can shorten the extraction duration and lower the extraction temperature.

Key words: snap bean, saponin, ultrasonic, extraction