Abstract: In this study, the fruit-spikes of Prunella vulgaris L. were used as raw materials to extract rosmarinic acid-3-O-glucoside by ultrasonic cell grinder extraction and the content was determined by HPLC. Through the investigation of various factors, the best extraction conditions were as follows: 50% ethanol as extraction agent, liquid-solid ratio of 25 mL·g⁻¹, cavitation time of 1.5 s, buffer time of 2.0 s, ultrasonic irradiation power of 300 W, ultrasonic irradiation time of 7 min. Under the optimum conditions, the yield of rosmarinic acid-3-O-glucoside was 0.71 mg·g⁻¹. Compared with the traditional extraction method, ultrasonic-assisted extraction has the advantages of stability, high efficiency and energy saving.