The invention discloses a building block cutting system for construction. The building block cutting system for construction comprises a base plate, a recovery system, a supporting plate, a motor device, a support device, a pushing device, a cutting device and an air cylinder device. A first supporting rod, a first bent rod, a first recovery box and a first positioning block are installed on the base plate. The recovery device comprises a second recovery box and a second positioning block. A first through hole, a second through hole, a frame, a first support and a first idler wheel are installed on the supporting plate. The motor device comprises a second supporting rod, a second support, a third supporting rod, a third support, a motor, an output shaft and a bracing wire. The support device comprises a fourth supporting rod, a fourth support, a second idler wheel, a first slanting rod and a second slanting rod. The pushing device comprises a first cross rod, a pushing plate, a first spring and a first fixing ring. the cutting device comprises a rotary rod, a first fixing block, a fifth support, a first connecting rod, a cutting wheel, a second spring and a third slanting rod. According to the building block cutting system for construction, building blocks can be cut quickly and effectively, cutting efficiency is high, and cutting is quick.