The invention discloses a grain crushing device. The grain crushing device comprises a workbench and a groove arranged in the workbench, wherein a grain storage hopper is arranged above the groove; a wheel carrier group is arranged at each of the left side and the right side of the workbench respectively; a crushing unit is arranged on each of the two wheel carrier groups, and lapped with the groove in the workbench; a drive unit used for driving each crushing unit to move is arranged at each of the front side and the rear side of the workbench, and composed of a drive crushing mechanism and a driven crushing mechanism which are arranged on the corresponding wheel carrier group; and a controller is arranged on the workbench, and electrically connected with the drive units. The grain crushing device disclosed by the invention has the beneficial effects of being simple in structure and high in practicability.