Abstract: The cycle stress ratio is the ratio of dynamic strength and soil static strength, as it passes the critical cycle stress ratio,accumulated deformation takes on and soil strength declines.According to researches about the Yellow River Delta, on the Yellow River Subaqueous Delta, the soil strength distribution is not homogeneous, so the critical cycle stress ratio of superficial soil is different. In the action of the storm wave load, the low strength soil, which passes critical cycle stress ratio, would be weaker and the high strength soil could keep stable. The flume experiment shows that the low strength soil in the action of wave shearing force would slide, as the result, strong erosion happens on the bottom. In conclusion, low strength soil is weaker in the action of storm waves, slide in the action of wave shear force and is took away by the bottom current. Then,Local defferential erosion Geomorphology appears on the Yellow River Subaqueous Delta.