Abstract: In order to study a method of promoting seed germination of Saposhnikovia divaricate seed by ultrasonic induction, in this article, single factor experiments were carried out based on ultrasonic time, ultrasonic power, water bath temperature, ultrasonic frequency and seed soaking time. Based on the single factor experiment, Plackett-Burman Design（PBD） was used to screen the key factors, and the central point of the key factors was obtained through the climbing experiment. Optimize key factors and conditions in combination with Box-Behnken Design（BBD） response surface, the best ultrasonic-induced seed germination factors of the Saposhnikovia divaricata seed were: ultrasonic time 16 min, ultrasonic power 62 W, water bath temperature 35 ℃, ultrasonic frequency 40 Hz, seed soaking time 2 d, and the expected germination rate and expected occurrence probability were 68.21% and 98.70%, respectively. Under this condition, the germination rate of Saposhnikovia divaricate seed was 65.66%, the relative error was 3.74%. Compared with the CK group, the germination rate, germination potential and germination index of the experimental group were better than those of the CK group, and the germination rate was finally increased by 29.71%. The results of ultrasonic induction treatment and scanning electron microscope of CK seed coat showed that the blockage degree and permeability of seed coat stripe cracks could be greatly improved by "cavitation effect" produced in the process of ultrasound. Research showed that ultrasonic treatment had a positive effect on Saposhnikovia divaricate seed germination.