Objective: To optimize allantoin extraction method from Dioscorea opposita Thunb. Methods: Using allantoin content as the indexes, 20% ethanol and methanol ultrasonic extraction, 20% ethanol and methanol reflux extraction and water formulation samples were determined by HPLC. Results: The allantoin content: Methanol ultrasonic extraction 2 times 〉 20% ethanol ultrasonic 2 times 〉 methanol ultrasonic 1 time 〉 20% ethanol ultrasonic 1 time 〉 methanol reflux 1 time 〉 20% ethanol reflux 1 time 〉 water reflux 1 time. Conclusion: Methanol ultra...