Abstract: 【Objective】 To investigate the physiological changes and transcriptome sequencing in the stems of Nymphaea ‘Blue Bird’ cut flowers during vase life, which could elucidate the molecular mechanisms underlying stem ben-ding during vase life and provide theoretical reference for breeding water lily varieties resistant to stem bending. 【Method】 Cut flowers of Nymphaea‘ Blue Bird’ were subjected to vase-holding experiments. Physiological parameters were measured daily at fixed intervals.Based on bending severity of water lily,stems were categorized into 4 developmental periods（designated as Dorsal_1,Dorsal_2,Dorsal_3 and Dorsal_4）.Soluble sugar and starch contents were detected in dif‐ferent samples.Transcriptome sequencing was performed to screen differentially expressed genes（DEGs）.GO functional annotation analysis,KEGG signaling pathway enrichment analysis and K-means analysis were performed on DEGs to explore the key metabolic pathways and key genes that led to the stem bending of cut water lily.Quantitative real-time fluorescence quantitative PCR validated the consistency between gene relative expression and transcriptome data. 【Result】 Water absorption,water loss and water balance value exhibited an initial increase followed by a decline.The average stem elongation was 4.45 cm,accounting for 17.8%of original length.Starch content showed no significant difference between Dorsal_1 and Dorsal_2（P＞0.05）,but both were significantly higher than Dorsal_3 and Dorsal_4（P＜0.05,the same be‐low）,the starch content of Dorsal_3 samples was significantly higher than that of Dorsal_4.The numbers of DEGs in Dor‐sal_1 vs Dorsal_2 group,Dorsal_1 vs Dorsal_3 group,Dorsal_1 vs Dorsal_4 group,Dorsal_2 vs Dorsal_3 group,Dor‐sal_3 vs Dorsal_4 group were 5149,6903,5483,2456 and 269,in which down-regulated genes nembers were 2826,3822,3068,1313 and 113,up-regulated genes numbers were 2323,3081,2415,1143 and 156 respectively.There were112 shared DEGs in samples of 4 different stem bending periods.GO functional annotation and KEGG signaling pathway enrichment analysis showed that DEGs in stem bending water lily was mainly enriched in biological pathways related to photosynthesis,cell wall synthesis,plant hormones and signal transduction.The results of K-means analysis showed that DEGs were clustered into 9 classes （Class 1-Class 9）,25 DEGs were screened by Class 1 and Venn diagram,and 19genes related to the regulation of water lily stem bending were screened by Class 5.The results of real-time fluorescence quantitative PCR showed that the relative expression of DEGs was basically consistent with the transcriptome data. 【Conclusion】 The bending of water lily stems arises from the synergistic interactions among multiple factors,including water,starch and soluble sugar contents,light responsiveness,phytohormones,cell wall biosynthesis and degradation.It is hypothesized that auxin related genes and cell wall structural related genes form critical gene clusters responsible for regu‐lating stem bending of water lily.