Abstract: Double flower is characterized by the increase in the number of petals, the folding of petal or the increase in area of petal, which usually has higher ornamental and economic value. Focusing on the increased number of petal and petal-like organ in double flower, we summarized and discussed the molecular mechanism of the formation of double flower in some model plants and ornamental plants, including the key transcription factors and the epigenetic modifications such as miRNAs, DNA methylation, histone modification and chromatin remodeling involved in the regulation of petal number. In the final part of this review, we discussed the developing trend of the future research of molecular mechanism of petal doubling of flower in ornamental plants.

Key words: double flower, epigenetic modification, floral organ development, MADS-box, transcription factor