The utility model discloses a class bank is chosen to differential type for reduce the water flow scouring in dam body low reaches, it is including setting up a class bank is chosen to the arc in dam body low reaches, and sets up on class bank is chosen to the arc, be used for choosing a class tooth to a plurality of circular arc camber of the dam body left and right sides and vertical diffusion respectively with the rivers in dam body low reaches. Implement the technical scheme of the utility model, partly rivers that a plurality of circular arc camber chose in the feasible rivers of flowing through of class tooth collide mutually with the both sides rivers, have improved the efficiency rate of dam body. This a plurality of circular arc camber chooses class tooth still makes another the part rivers in the rivers flow through take place vertical diffusion in the same direction as water flow direction, has increased energy dissipation, has reduced the overflow unit area energy that entries, alleviates the local scour to the damsite low reaches.