Orchid composite extract and use thereof in preparation of composition having anti-depression effect

The present invention relates to an orchid composite extract, which comprises a volatile aroma compound, and the volatile fragrance compound includes several dimethyloctene compounds and other inseparable ingredients. The orchid composite extract, which can be administered to a subject in need for a continuous duration, can improve the brain connectivity and autonomic system (ANS) of the subject, as well as regulate the subjective feeling of the subject, thereby being as an effective ingredient for use in the preparation of a composition having anti-depressant effect.