When the vibration grading sieve moves, the motor drives the eccentric exciter via the triangular belt thereby making the sieve bed move reciprocally in an asymmetric manner. As the material layer on the sieving surface becomes loose, finer aggregates fall down through the layers and separate through the sieve hole, shaking out the material that stick in the sieve. At the same time, finer aggregate moves downward and discharge through the sieve holes.