Abstract: In order to explore the role of WALLS ARE THIN（WAT1） in wood formation and response to stress in woody plants, bioinformatics tools was used for analysis, and quantitative Real-time PCR（qRT-PCR） was used to investigate the expression patterns of EgrWAT1L and EgrWAT1S in different tissues, internodes and in response to different stresses, and the gene EgrWAT1S and its other transcript EgrWAT1L were cloned from Eucalyptus grandis. The results showed that the EgrWAT1S was highly expressed in phloem, while EgrWAT1L was mainly expressed in roots, and the expression patterns were significantly different under methyl jasmonate（MeJA） and salicylic acid（SA） treatment, salt stress, phosphorus（P） and boron（B） deficiency, and even opposite under MeJA and SA. These results suggested that EgrWAT1L might affect EgrWAT1S expression through transcriptional regulation and further protein translation in response to hormone and stress treatments.The studies provided a basis for further elucidate the function in the growth and development of EgrWAT1 gene and also provided a possibility for future molecular breeding of Eucalyptus.