Abstract:ObjectiveTo optimize the extraction process of volatile oil in Michelia hedyosperma Lew by orthogonal design.Methods Using the volume of volatile oil as the index and the screen mesh of medicinal materials, the ratio of solid to liquid and soaking time as affecting factors the orthogonal experiment was conducted.Results The optimized extraction process was as follows: medicinal materials which screen mesh were 16, the ratio of solid to liquid 1∶10 being soaked in the water for 20 hr and distilled with vapour.Conclusion The optimized extraction process is simple and practicable.