Abstract This study exploring the molecular mechanism of stamen petaloid development of Alcea rosea L., a popular ornamental of the region, using a comparative transcriptome analysis between multi-petal red flowers (stamen petaloid) and single petal red flowers (no-stamen petaloid) by RNA-seq technology fetched interesting observations. It is found that the 3375 differently expressed unigenes (DEGs), out of the total 132,569 unigenes, including 1550 were up-regulated and the remaining 1825 were down-regulated at the transcript levels. The average length of these DEGs was 741 bp, and the N50 was 1090 bp. A large number of DEGs related to stamen petaloid were identified by GO and KEGG annotation. Some of them get involved in the synthesis and signal transduction of plant hormones, such as auxin, gibberellin, cytokinin, ethylene, and brassinosteroid, while others are closely related to some key transcription factors, such as bHLH, MYB, GATA, MADS-box. These DEGs provide important clues of the regulatory pathway and offer valuable information for studying the mechanism of stamen petaloid.