Objective:The effect of ultrasonic-assisted ionic crosslinking method on the peppermint capsule roundness was studied. Methods:The optimal treatment process was obtained through response surface optimization method, and the quality indicators of peppermint capsule was analyzed. Results: The results showed that, the optimum conditions of ionic crosslinking method were calcium ion mass fraction of 0.4%, soaking time of 20 min, solid/liquid ratio of 1.3∶1.0 (mL/g). Under the conditions, the strength of wet-capsule was 11.5 N, and the roundness of capsule was 0.033 mm. The optimum conditions of ultrasonic-assisted ionic crosslinking method were: ultrasonic time of10 min, ultrasonic power of 105 W, ultrasonic temperature of25 ℃. Under the conditions, the strength of wet-capsule was14.7 N, and the roundness of capsule was 0.028 mm. Conclusion: Compared with the traditional ionic crosslinking method, the strength of the wet-capsule was increased by 27.8%, the roundness of the capsule product was decreased from 0.075 mm to0.028 mm, and the product yield was increased from 83.7% to 98.3%, which showed that the quality of the peppermint capsule was obviously improved. The ultrasonic-assisted ionic crosslinking has the advantages of simple process and high efficiency, which could provide a reference for the development of capsule preparation technology.