Objective: To determine the optimal extracting process of the volatile oil for Biyuan Dropping Pills.
Methods: Conditions for the extraction were studied by orthogonal design guided by the increasement of the volatile oil.
Results: The distilling time is the main factor,and the fineness of the herbal material is the second. The optimal process is as follows: crush the herbal material into coarse powder, macerate 1 hour with 9 times water and distill 4 hours.
Conclusion: The optimized process is feasible and stable.