Mangroves play an important role in protecting coastal zones due to the capacity of reducing tidal-wave energy. At the same time, biological properties of mangrove is heavily affected by the variation of the tidal regime. The study was done to assess impacts of inter-tidal wave on the mangrove structure in the Bac Lieu coastal zone of the Vietnamese Mekong Delta. Three standard-plots with the area of 400m² (20m × 20m) were set for each transect, ranged from the edge facing the sea to further inland. In total, three transects were measured to ensure the representation of the study area in terms of species composition, trees density and trees height, trunk diameter, and root density and height. The density, height and diameter of mangrove trees distributed relatively evenly, ranging from 183 to 218 tree per standard-plot and tended to decrease with the inter-tidal. The mangrove root density was not affected by the tidal regime; however, the density of mangrove root height were different at different inundation depths. The density of high root at the area of the high inundation depth was of the greatest (100 root.m^-2); however, the density of medium and low root (corresponding to 93.56 root.m^-2and 94.33 root.m^-2, respectively) were dominant at the low inundation depth.