There is narrow valley,steep slope and flat and straight channel in the dam site of Youchou Hydropower Station.And the flood peak is high and the discharge is large.The energy dissipation problem of the downstream of the station is remarkable.By the comparative analysis of hydraulic calculations and model test,the results show that the plan of flaring pier underflow energy dissipation had the feathers of high energy dissipation rate and stable tail water which is a good solution to the energy dissipation problem of big unit discharge and lowa Froude number.