The invention discloses a floral organ specific expression promoter separated from Populus trichocarpa Torr.&Gray and application thereof, belonging to separation and application of a promoter. The nucleotide sequence of the promoter is shown as SEQ ID NO.1. The invention also discloses a recombinant plant expression vector and recombinant host cell containing the floral organ specific expression promoter. Functional verification tests discover that a GUS gene driven by the promoter only performs specific expression in sepals and petals of tobacco, and no GUS expression activity exists in roots, stems, leaves, stamens, carpels and other tissues of the tobacco, thus indicating that the promoter separated from Populus trichocarpa Torr.&Gray is the floral organ specific expression promoter. The invention further discloses application of the floral organ specific expression promoter in the aspects of improving plant traits, cultivating new plant species, studying floral organ development and regulation mechanisms of plants and the like.