Abstract: The changes of endogenous hormone contents in leaves and stems of two cultivars of the water bamboo(Zizania latifolia)during growth and development were studied,and dry weight of swollen culms were also measured. The results showed that the content of Z+ZR was highest at different developmental stages and parts,followed with IAA. The contents of GA₃ and ABA were very low. Generally levels of hormones were highest in culm,followed by sheathes and leaves the lowest.The content of Z+ZR rose obviously and descended rapidly before and when gall started on swelling,respectively. The content of IAA in leaves was descending from anaphase to telophase of gall’s swelling. The content of ABA in leaves was raised just before gall’s swelling and that in sheathes was raised in anaphase of the gall’swelling,but there’s no visible change in culm. There was no obvious change of GA₃ content in all parts and during growth and development. Very close relationship between increase of dry weight of swollen culm and the content of Z+ZR was found. It is concluded that Z+ZR was the key hormone in gall’s shaping. The differences in hormone contents of every part and its changes were observed between cultivars,especially in the swelling period of gall.