The invention discloses a rapid grinding device for building steel with a fixed size, and relates to the field of building engineering. The rapid grinding device for the building fixed-size steel comprises a fixing frame, the top of the inner wall of a rotating sleeve is rotationally connected with a rotating disc, the lower surface of the rotating disc is rotationally connected with the upper surface of the fixing sleeve, a first rotating ferrule is rotationally connected with a first limiting rod, and the fixing sleeve is in rolling connection with a second rotating ferrule. And the second rotating ferrule is rotationally connected with the second limiting rod. According to the rapid grinding device for the building steel with the fixed size, by arranging a first connecting shaft, a rotating sleeve, a first rotating ferrule and a limiting block, the device does not need to be taken down to change the angle, the working efficiency is improved, a plurality of workpieces can be ground at the same time, and the grinding error of the workpieces of the same kind is reduced; the workpiece sequentially passes through the first grinding device and the second grinding device, the grinding speed is increased, and grinding of workpieces of the same size is facilitated.