The river bank landslides is happening throughout in Vietnam. There are many causes of river bank landslides such as velocity of flow, waterway, the increase in load along the bank, the depletion of sediment and the influence of permeability flow. This study assesses the impact of the permeability flow to the stability of the river bank slope, a case study on Ong Chuong river - An Giang province. Soil mechanical properties and soil permeability coefficient are used to analyze and calculate the saturation line of permeability, using the results from the permeability model to calculate stability slope of river bank. Research results show that seepage flow is one of the causes of instability of the river bank slope, especially in the case of rapid retreat of river water levels during the flood season.