Alien tree species play significant roles in forestation and conservation of soil and water. Due to their fast growth-induced high water consumption and drought resistance characteristics, many alien tree species have affected and even damaged native forest ecosystems, and some species have been reported to be the noxious invasive species. These alien tree species have caused significantly environmental problems. Regarding water consumption of alien tree species, we reviewed their water use strategies in scales of ecosystem, whole tree, leaf and branch. We also analyzed their impacts on underground water quality and nutrient cycling, and water resource of local forest ecosystem. The results demonstrate that the alien tree species usually consume more water than local native species at whole-tree and ecosystem levels, and the hydraulic adjustment of alien trees to different soil water availability are presented mostly at leaf and branch level. However, it is not necessarily to prove that they have the negative impacts on local water resources as such impacts are closely associated with many factors including environment, climate and tree individual characters. At last, in order to improve the water use research and risk assessment of alien tree species, we proposed several research concerns in the near future. Firstly, precisely evaluating the effects of alien trees on water resource largely depends on the well-recognition of their water use regulation, therefore both the evaluation and regulation studies should be strengthened. Moreover, applying key water use characteristics in risk assessment systems and in alien tree species database construction could be considered as efficient and important pathways not only for invasion plants control, but also in forestation water management. This review is applicable for forest managers and government to balance the economic and ecological outcomes of alien trees, and to improve ecological safety.