The invention discloses a stone crushing device used in hydraulic engineering. The stone crushing device comprises a foundation rectangular base. The upper end of the foundation rectangular base is provided with a primary stone crushing box body and a secondary stone crushing roller device. The upper end of an inner cavity of the primary stone crushing box body is provided with a primary stone crushing device which is composed of a rectangular groove, a first fixing bearing, a sliding bearing, a rotating shaft, a roller, a driving device and a roller displacement adjusting device. The roller displacement adjusting device is composed of a rectangular opening, an adjusting rod, a connection rod, a first screw hole, a second screw hole and an adjusting screw rod. The secondary stone crushingroller device is composed of a supporting base, a second fixing bearing, a stone crushing roller, a stone crushing block, a circular discharge outlet, a rectangular through groove, a net sieve and a driving assembly. The lower end of the inner cavity of the primary stone crushing box body is provided with a feeding device which is composed of a circular feed inlet, an inclined supporting bottom plate, a screw rod and a first driving motor. The stone crushing device has the beneficial effects of being simple in structure and high in practicability.