The invention provides an anther-specific expression promoter in plant, wherein said promoter is a promoter of Oncidium aureusidin synthase gene OgAS1, and has a sequence as SEQ ID No: 3. The invention provides further a gene expression cassette that comprised a promoter having a DNA sequence as SEQ ID No: 3, and a polynucleotide that encode an open reading frame and is linked to the 3' end of said promoter, wherein said promoter can activate the transcription of said polynucleotide in an organism containing said gene expression cassette. The invention provides also a gene expression vector that contains a promoter having DNA sequence as SEQ ID No: 3. The invention provides further a process for producing a transgenic plant or part of organ, tissue or cell of said transgenic plant containing the above-described gene expression cassette.