Abstract: The slow growth of Lycoris radiata bulbs under natural conditions severely restricts the development of the Lycoris industry. Understanding changes in endogenous hormone regulation during bulb development could provide a theoretical basis for accelerating bulb enlargement through the application of exogenous hormone. In this study，four groups of developing Lycoris radiata bulbs with the same genetic background were developed and used to investigate changes in the content of four endogenous hormones：auxin，cytokinin，gibberellin，and abscisic acid. The expression patterns of the genes involved in hormone biosynthesis and signal transduction were also examined through transcriptome analysis. The results showed that endogenous gibberellin could negatively regulate the development of Lycoris bulbs，while endogenous auxin and cytokinin positively regulated development. Auxin mainly affected the early stage of bulb development and may act by regulating gene expression patterns related to cytokinin synthesis and signal transduction. The results also suggested that endogenous abscisic acid had little effect on the regulation of bulb development in Lycoris radiata. Finally，the study showed that genes related to jasmonic acid（JA）and salicylic acid（SA）were up-regulated during bulb development，implying that the regulation of JA and SA may be positively correlated with bulb development of Lycoris radiata.

Key words: Lycoris radiata, bulb development, transcriptome analysis, IAA, GA, ABA