Eucalyptus urophylla × Eucalyptus grandis and bamboo-willow have attracted wide concerns due to the debates on their water consumption (WC) and utilization efficiency problems. Insufficiency of scientific observation data and consequent uncertainty of the rationality of blame or support on the two trees' development make it a necessity to further study their WC characteristics and water use efficiency (WUE). In this study, WC and water consumption rate (WCR) of E. urophylla × E. grandis and bamboo-willow seedlings under different soil moisture conditions were measured by pot seedling weight method, and net photosynthetic rate (Pn), transpiration rate (Tr) and WUE of them in different growth periods were investigated by Li-6400 photosynthetic system measuring method. Under normal water condition, day-and-night WC and maximum WCR of E. urophylla × E. grandis and bamboo-willow seedlings were(182.05±12.74)g/d,(100.48±10.95)g/d, (66.31±9.91)g·m^-2·h^-1 and(89.50±13.54)g·m^-2·h^-1, respectively. Water consumption and WCR of the seedlings significantly declined with soil moisture decreases, with those of E. urophylla × E. grandis declining more sharply than bamboo-willow under serious drought stress. The daily variation of WCR exhibited a one-peak curve (the peak appearing at 12:00-14:00) under normal water condition and light drought stress, but changed to a double-peak curve (the peaks appearing at 10:00-12:00 and 14:00-16:00, respectively)under moderate drought stress, and showed no regular pattern under serious drought stress. Under normal water condition and light drought stress, a significant positive correlation and a significant negative correlation were observed between WCR and environmental temperature and between WCR and relative humidity, respectively. The influence of environmental factors on WCR weakened along with the development of drought stress. At leaf level, bamboo-willow had higher photosynthetic rate and WUE, and lower transpiration rate than E. urophylla × E. grandis. In initial through vigorous growth period, net photosynthetic rate and transpiration rate of both seedlings increased at similar amplitude, while their WUE remained unchanged. In terms of WC and WCR of individual seedling and leaf WUE, bamboo-willow was a good water-saving fast-growing tree species. E. urophylla × E. grandis had higher leaf transpiration rate and lower WUE at leaf level, but had lower WCR at individual seedling level than bamboo-willow, which was particularly true when under serious drought stress, with its average daytime WCR being only (4.02±0.60) g·m^-2·h^-1. Therefore, E. urophylla × E. grandis seedlings also showed a certain ability of drought resistance and water-saving.