Root is the link between plants and soil, and also the organ for plants to absorb water and nutrients. It plays a vital role in the physiological activities of plants. Poplar is widely planted in plain of North China, and the wood output accounts for almost 30% of the total wood output in China. Therefore, understanding the characteristics of poplar root is conducive to the in-depth understanding of its survival and growth mechanism, ecological adaptation strategies in various environments, so as to provide a theoretical basis for the optimization of efficient management technology of poplar plantation and the improvement of forest quality and forest yield. In this paper, based on the existing studies, the contents of poplar root morphology, distribution, dynamic characteristics, water absorption characteristics and some research methods are reviewed. Firstly, various root classification methods used in previous studies were discussed, then their shortcomings and merits and more suitable methods for poplar root classification were pointed out. Secondly, the various architecture, morphology, distribution and growth dynamics of poplar root found in existing studies were summarized, and the causes of various characteristics and their effects on the absorption efficiency of poplar root were discussed. Finally, the water absorption characteristics and mechanism of poplar root under various conditions were summarized, the deficiencies of existing research on poplar root and the future research direction were also put forward.