An ultrasonic-assisted extraction (UAE) method based on the acidic ionic liquid (IL) of 1-methyl-3-H-imidazolium hydrogen sulfate ([HMIM][HSO4]) has been successfully developed to extract leonurine from Herba Leonuri. The results indicate that the acidity of the IL has remarkable effect on the extraction efficiency. In addition, several parameters affecting the extraction efficiency, such as ultrasonic power and time, concentration of IL and solid-liquid ratio, were also optimized. Using the proposed approach, the extraction efficiency of leonurine from Herba Leonuri powder reached 0.136 parts per thousand within 30min using only 20mL of 1molL(-1) [HMIM][HSO4] aqueous solution.