The invention relates to a newly discovered DNA sequence which can be used as a promoter for regulating and controlling a target gene to be specifically expressed in a floral organ of arabidopsis thaliana. An AtcpSecY1 gene promoter sequence is cloned from a model plant arabidopsis thaliana; subsequently in a transgenic arabidopsis thaliana, the promoter is confirmed to be capable of driving a GUS reporter gene to be specifically expressed in the floral organ of arabidopsis thaliana. With the application of the promoter, a 'floral organ specificity promoter-target gene to be expressed' fusion gene is obtained by construction, arabidopsis thaliana is transformed, and the transgenic plant having the target gene specifically expressed in the floral organ can be obtained. The promoter not only provides important molecular elements for in-depth research of plant floral organ differentiation, formation, growth and development molecular mechanisms and other theory researches, but also provides important molecular regulating and controlling elements for plant genetic engineering seed breeding, especially the gene engineering seed breeding for regulating and controlling flower shapes, flower colors, flower aromas, ornamental life and the like of famous and valuable flowers, and has wide application value.