The invention discloses a main shaft transmission system of a side sweeping machine. The main shaft transmission system comprises a workpiece clamping block I, a workpiece pressing shaft, a workpiecepressing shaft sleeve, hinges, connection rods, a bracket, a cylinder, a lower disk support, a lower disk shaft sleeve, a driven gear, a main bracket, a speed reducer, a speed reducer seat, a bottom plate, a motor belt wheel, a motor, a V belt, a speed reducer belt wheel, a driving gear, a lower disk main shaft, a servo motor, a motor mounting seat, a driving synchronous belt wheel, an unloading disk, a synchronous belt, a driven synchronous belt wheel, a workpiece rotating shaft and a workpiece clamping block II. The main shaft transmission system of the side sweeping machine can automatically turn over another edge after one edge of a workpiece is polished to shorten the time of the whole edge polishing procedure, thereby improving the machining efficiency; and the whole workpiece can rotate around the center of the main shaft and do planet-like motion, so that the workpiece is in more uniform contact with a polishing disk, knife grains on the workpiece and the speed and the direction of the polishing disk are disordered, and the polishing precision and the removal amount are effectively improved.