The present invention provides a Piper laetispicum extract, the preparation method therefor and the use thereof. The Piper laetispicum extract includes: sesamin; (2E,6E) -N-isobutyl-7- (3,4-methylenedioxyphenyl) heptadienamide; (2E, 4E) -N-isobutyldodecane-2,4-dieneamide; (2E, 4E) -N-isobutyl-15-phenylpentadeca-2,4-dieneamide; (2E, 4E, 14Z) -N-isobutyleicosane-2,4,14-trienamide; and (2E, 4E) -N-isobutyl-13-phenyltrideca-2,4-dieneamide. The Piper laetispicum extract can prevent depression.