Root system is the main organ for plants to obtain water, which directly affects the water transfer and life activities of the whole plant. Under the condition of water shortage, it has always been a hot topic in the research and innovation of water-saving irrigation technology to understand the water demand characteristics in the process of root growth and improve the utilization rate of agricultural water resources. Therefore, it is necessary to accurately estimate the water absorption capacity of plant roots in the research process, and the establishment of a water absorption model is an important method to quantitatively study the water absorption characteristics of plant roots. The principle of root water absorption and its main influencing factors were summarized, the root water absorption models were classified under different research methods, and their applicable scope, advantages and disadvantages were expounded, and the root water absorption models were introduced under the combined stress of water and salt. Finally, the current root water absorption model was analyzed, and the future research direction was proposed. The research results provid the basis for building a three-dimensional dynamic water absorption model of rice roots.