To investigate characteristics of the root systems of the plants that constitute the vegetation in the water-level-fluctuation-zone of the Three Gorges reservoir region and their relationship with anti-erodibility of the soil, 6 flooding-tolerant plants, i.e. Cynodon dactylon(L) Pers., Alternanthera philoxeroides (Mart) Griseb, Triarrhena sacchariflora Nakai, Hemarthria compressa(L.f.) R. Br., Cyperus rotundus L., and Arundinella anomala Steud, were selected as subjects for the study. Root-soil core samplers (Eijkelkamp Agrisearch Equipment Model 15.01) were used to take samples from the fields for analysis, a modified hydraulic flume device to analyze the soil samples for water erosion rate and for calculation of anti-erodibility enhancement coefficients of root systems of the 6 plants and the Root Analysis System (WinRHIZO Pro. 2004c) to characterize the root systems. It was found that Alternanthera philoxeroides (Mart) Griseb, Triarrhena sacchariflora (Maxim.) Nakai, Cyperus rotundus L., and Cynodon dactylon (L.) Pers. were relatively higher in mean root/shoot ratio, while Arundinella anomala Steud. and T sacchariflora were in root length density (RLD) and root surface area density (RSAD), and that soils containing roots was obviously lower in soil erosion rate. A. philoxeroides, T. sacchariflora and A. anomala were significantly higher than the other three in anti-erodibility enhancement coefficient (Ec), which was in significant linear regression relationship with RLD and RSAD. Among the root system, particularly roots with D ≤ 2 mm was closely related with soil anti-erodibility, and their RLD and RSAD were in significant linear regression relationship with Ec with correlation coefficient declining with increasing root diameter. It was also found that all the six plants significantly enhanced soil anti-erodibility and A. philoxeroides, T. sacchariflora and A. anomala were the most effective. RLD and RSAD are good indexes to characterize soil anti-erodibility, especially RLD and RSAD of roots with D ≤ 2 mm or D ≤ 0.5 mm and hence the most important parameters in characterizing soil anti-erodibility.