Objective: To discuss the function and effect on the application of β-cyclodextrin to mask the smell of stench in Hirudo raw powder.Method: GC analysis was used to test the inclusion effect of β-cyclodextrin on hexanal and trimethylamine

respectively.And dissolution changes of hexanal and trimethylamine in Hirudo raw powder before and after being treated with β-cyclodextrin were analyzed by GC.Result: Hexanal and trimethylamine were attributed to the main stench compounds in Hirudo raw powder

and their contents were 0.02

0.09 mg · g-1

respectively.Hexanal and trimethylamine were not detected in aqueous phases of hexanal inclusion complex with β-cyclodextrin

and only trace trimethylamine was detected in aqueous phases of trimethylamine inclusion complex with β-cyclodextrin.Meanwhile

both of free hexanal and trimethylamine were not detected in aqueous phases of mixed Hirudo powder by co-grinding with β-cyclodextrin.Conclusion: As representative of low molecular stench components

hexanal and trimethylamine can be efficiently included with β-cyclodextrin

and β-cyclodextrin can be applied as an odor masking agent to effectively mask unpleasant smells in traditional Chinese medicine preparations when added properly in the production.