The invention discloses a rebar cutting and polishing device for buildings. The rebar cutting and polishing device comprises a cutting device, a drying device and a polishing device, wherein a dust collecting box is arranged at the upper end of the cutting device, a first exhaust fan is arranged on the left side of the dust collecting box, a metal sized hose is arranged at the upper end of the dust collecting box, three second exhaust fans which are distributed at equal intervals are arranged at the upper end of the drying device, a heating device is connected to the lower ends of the exhaust fans, an alkali liquor tank, a water tank and an acid liquor tank are sequentially arranged on the upper side of the polishing device from left to right, the lower end of the alkali liquor tank, the lower end of the water tank and the lower end of the acid liquor tank are each provided with an atomizer, the left side of each atomizer is provided with a third exhaust fan, and the bottom of the polishing device is provided with three polishing wheels which are matched with the alkali liquor tank, the water tank and the acid liquor tank. According to the rebar cutting and polishing device for the buildings, the problems that rusted rebars are difficult to polish, and polishing is not thorough are solved, the polishing efficiency is high, and lengths of the rebars can be flexibly cut.