Abstract: The seepage in riverbank generally induces the bank-collapse so it is one of the key points in the research of this area.The seepage analysis now is based on the assumption that the flows inside and outside the bank slope are too slow to be considered,which ignored the fact that the flow velocity in the river is rather high,eg.2.5~4.5 m/s in the Yangtze River,China.A new experimental equipment is developed to invest igate the effect of flow velocity on the seepage in riverbank A series of tests are performed by combining various flow velocities and seepage heads.The test results indicat that the flow velocity obviously affects the seepage in the sand soil.When the seepage gradient at the seepage exit is lower than a certain value,the flow will weaken the seepage discharge; if the seepage gradient is higher than the certain value,the flow will increase the seepage discharge.The research will benefit the safety evaluation of the constructions along rivers.