Abstract: Abstract: Soil erosion and bank degradation is a major post-dam concern regarding the riparian zone of Three Gorges Reservoir (TGR). The development and succession of vegetation are the main countermeasures, especially to enhance bank stability and mitigate soil erosion. Thus, the role of for Cynodon dactylon (L.) Pers. and Hemarthria altissima (Poir.) Stapf et C. E. Hubb. in wave attenuation and erosion control was measured via the flume experiments. The results showed that the two grass species play an important role in wave attenuation and erosion control. The effects of wave attenuation and erosion control capabilities for the two species were different. The mean wave dissipation coefficient (MWDC) for Cynodon dactylon (L.) Pers. and Hemarthria altissima (Poir.) Stapf et C. E. Hubb. were 0.37 and 0.30, respectively, with the wave period of 1.2 s to 1.5 s. Nevertheless, the values of MWDC for Hemarthria altissima (Poir.) Stapf et C. E. Hubb. was similar to Cynodon dactylon (L.) Pers. (ranged from 0.15 to 0.30) when the wave period was between 0.8 s to 1.2 s. The MWDC values of 0.43 and 0.30 were responded for Cynodon dactylon (L.) Pers. under 80% and 40% area coverage, respectively. In contrast, the MWDC values for Hemarthria altissima (Poir.) Stapf et C. E. Hubb. were 0.35 and 0.24, respectively, under two different coverage. The MWDC values for Cynodon dactylon (L.) Pers. with a wave height of 8 and 4 cm were 0.34 and 0.39, respectively; whilst, the ones for Hemarthria altissima (Poir.) Stapf et C. E. Hubb. were 0.15 and 0.32, respectively. The MWDC values showed generally increasing trend with increasing wave period. Species studied also significantly reduced wave induced soil erosion. The results of washout tests indicated the soil erosion modulus decreased with increasing eroded time. The largest erosion modulus was measured for bare land (799.40 g/(m2·min)), followed by Hemarthria altissima (Poir.) Stapf et C. E. Hubb. (57.28 g/(m2·min)), Cynodon dactylon (L.) Pers. (17.63 g/(m2·min)). When the wave height was 8 cm, the mean erosion modulus was 84.81, 224.82 and 1 746.67 g/(m2·min) for Cynodon dactylon (L.) Pers. samples, Hemarthria altissima (Poir.) Stapf et C. E. Hubb. samples and bare land, respectively; whereas, the mean erosion modulus for wave height equal to 4 cm was 13.54, 22.67 and 656.8 g/(m2·min), respectively. The percentage erosion control effectiveness of the two species studied ranges from 89.0% to 98.6%. Erosion control effect for Cynodon dactylon (L.) Pers. was found a bit higher as compared to that for Hemarthria altissima (Poir.) Stapf et C. E. Hubb. under the same test conditions, but not significantly different. Erosion reducing is a combined consequence of above-ground and root system. The relative contribution rates of roots for Hemarthria altissima (Poir.) Stapf et C. E. Hubb. to prevent soil from erosion was as high as 91%, while its shoots only contributed the proportion of 7.4% to 8.6%; Roots of Cynodon dactylon (L.) Pers. afforded a smaller soil conservation contribution rate than Hemarthria altissima (Poir.) Stapf et C. E. Hubb., whilst its aboveground contribution rate, ranged from 23.8% to 28.8%, was significantly higher than Hemarthria altissima (Poir.) Stapf et C. E. Hubb. In summary, the capability of wave attenuation and erosion control for Cynodon dactylon (L.) Pers. was better as compared to the Hemarthria altissima (Poir.) Stapf et C. E. Hubb, which recommending Cynodon dactylon (L.) Pers. as a better selection for soil conservation in the riparian zone of TGR. The efficiency of wave dissipation and erosion reducing capacity for the investigated species were influenced by the vegetation coverage, the morphological features of aboveground and underground root system, the wave size and period. Combined with the knowledge of vegetation dynamics, ecological site properties, and species resistance to erosion, the observations made in this experiment would be useful for species selection in the context of ongoing and future revegetation activities in the riparian zone of TGR and similar riparian areas in the Yangtze River Basin.