The invention belongs to the technical field of crushers, and particularly relates to an automatic classification jaw crusher. The jaw crusher comprises a movable jaw, a main fixed jaw, a multi-stagefixed jaw, a power mechanism, a reciprocating mechanism, a vibration mechanism and a rack, wherein the movable jaw, the main fixed jaw, the power mechanism, the reciprocating mechanism and the vibration mechanism are all arranged on the rack. The crusher disclosed by the invention can classify stones according to sizes before the stones are crushed, and crushes the stones according to the sizes ofthe stones; the movable jaw swings once to crush the stones for multiple times; and after the stones are crushed for multiple times, flaky stones can be reduced. The invention further provides an application method of the crusher. The application method comprises the steps of adjusting a second crushing gap, locking the second crushing gap, swinging the movable jaw, vibrating the main fixed jaw and the like. The method is convenient to operate, simple and easy to understand and high in automation degree, the stone size classification standard can be changed, classified crushing is conducted according to the stone size, the crushing efficiency is high, the crushing effect is good, and the operability is high.