Abstract: Glyceraldehyde-3-phosphate dehydrogenase gene（GAPDH）was cloned from root tissues of cucumber（Cucumis sativus L.）line‘Zaoer N’with high waterlogging tolerance，based on reverse transcription polymerase chain amplification（RT-PCR）and rapid amplification of cDNA ends（RACE）methods. CsGAPDH gene contained an open reading frame（1 011 bp）and encoded a protein of 336 amino acids. Phylogenetic analysis of CsGAPDH gene showed high conserved character of GAPDH gene among different crops. CsGAPDH showed the highest homology with dicotyledonous plants such as carrot，grape and soybean，and the similarity were more than 88%. For monocot crops rice and maize，the similarities of GAPDH gene were 86.8% and 86%，respectively. The time course expressions of CsGAPDH gene in root of‘Zaoer N’under waterlogging treatment were determined by quantitative RT-PCR. CsGAPDH gene was ignificantly induced at 2 h after waterlogging treatment，and the peak level of gene expression was at 12 h. The tissue specific expression of CsGAPDH indicated that the expression level of CsGAPDH gene in root and leaf was higher than that in stem of the control plant；However，the transcription level of CsGAPDH gene were significantly up-regulated at 4 h after waterlogging treatment，which were higher in root than that in leaf and stem. In summary，the CsGAPDH gene was involved in waterlogging response in cucumber，and might play an important role in releasing waterlogging stress.

Key words: cucumber, waterlogging stress, CsGAPDH, induced expression