The invention discloses a shearing and grinding-flat integrated machine for building stones. The shearing and grinding-flat integrated machine for the building stones comprises a machine body. A machining platform is arranged on the machine body. The bottom end of the machining platform is provided with a bottom support through a support installation piece. The support installation piece is provided with an installation groove. An installation head at one end of the bottom support is movably installed in the installation groove through a connecting shaft. The shearing and grinding-flat integrated machine for the building stones has the beneficial effects that due to a cutter and an edge grinding band, cutting and edge grinding can be conducted at the same time, and the work efficiency is improved; motors, lead screws, air cylinders and piston rods are arranged, a transverse rod can move up and down, a moving loop bar can move left and right, the cutter can conveniently conduct shearing and cutting, and therefore the cutting effect is better; a water tank and spray nozzles are arranged, and therefore it can be effectively avoided that generated dust splashes in the process of shearing and grinding flat; the bottom support is arranged, the bottom support is movably connected with the machining platform through the support installation piece, so that the bottom support can be folded, and carrying is convenient.