Abstract-The study area lies in the subaqueous delta, which came into being in 1964～1976. Oneoil-field road has been built for exploring petroleum to form a wave barrier. The hydrodynamic conditionson the north side of the road are relatively violent, on the contrary the hydrodynamic conditions on thesouth side of the road are nearly placid. This makes the study area a natural laboratory for studying theinfluence of the hydrodynamic conditions on the fractal characteristics of the tidal flat. Selecting an areais named Case Ⅰ on the side of stronger hydrodynamic activities and an area is named Case Ⅱ on the otherside. Measuring the topography and sampling and analyzing the granulometrical comoposition, it is foundthat the hydrodynamic conditions have fatal influence on the surface fractal dimensions and the granulo-metrical fractal dimensions of the area. In Case Ⅰ, which has strong hydrodynamic conditions, the sur-face fractal dimensions are obviously large than those of Case Ⅱ, and the granulometr Abstract-The study area lies in the subaqueous delta, which came into being in 1964 ~ 1976. Oneoil-field road has been built for exploring petroleum to form a wave barrier. The hydrodynamic conditionson the north side of the road are relatively violent, on the contrary the hydrodynamic conditions on thesouth side of the road are nearly placid. This makes the study area a nearly laboratory test for the fluid condition on the fractal characteristics of the tidal flat. Measuring the topography and sampling and analyzing the granulometrical comoposition, it is found that the hydrodynamic conditions have fatal influence on the surface fractal dimensions and the granulo-metrical fractal dimensions of the area. In Case I, which has strong hydrodynamic conditions, the sur-face fractal dimensions are obviously large that those of Case , And the granulometr