The present invention relates to the field of garbage landfill. The present invention discloses a classified landfill device and method for garbage landfills, and the problem solved by the present invention is that the device proposed in the above background absorbs metals in the garbage using a magnet, but when the surface of the magnet has absorbed a large amount of metal, the device needs to be closed to treat the metal adsorbed on the surface of the magnet. The present invention comprises a screening mechanism, crushing mechanism and discharge mechanism. According to the classified landfill device and method for garbage landfill, the second crushing knife is set at an angle to divert the falling garbage to the front and rear sides, so that the two first crushing knives and the second crushing knife cooperate to crush the garbage respectively to avoid excessive accumulation of garbage.