The invention relates to a plate cutting device with an automatic rotating function. The plate cutting device comprises a workbench, one side of the workbench is provided with a clamping mechanism, the clamping mechanism comprises a support, a sliding block which is connected to the support in a sliding mode and a clamping piece which is arranged in the mode of rotating around the sliding block; and a steering mechanism is arranged on the surface of the workbench, the steering mechanism comprises a rotating shaft and a plate table which is fixedly connected to the top end of the rotating shaft, and a cutting mechanism is arranged on one side of the steering mechanism. The rotating shaft of the steering mechanism rotates by 90 degrees each time, so that when a plate with multiple edges required to be cut is cut, a lot of time and labor are saved, and the cutting efficiency is improved.