The invention provides an arc opening cutting rotating tool rest. The arc opening cutting rotating tool rest comprises a rack, a main beam, an auxiliary beam, a drive motor and a grinding disc. The rack comprises a left rotation connecting part and a right rotation connecting part. One end of the main beam is rotationally connected with the right rotation connecting part, and the other end of the main beam is rotationally connected with the left rotation connecting part. The area of one end portion of the main beam is connected with an overturning and swinging rod. The end portion of the overturning and swinging rod is connected with an overturning and swinging power mechanism used for overturning and swinging the main beam in a reciprocating manner according to the preset angle. The drive motor is fixed to the auxiliary beam. The output end of the drive motor is connected with the grinding disc. The drive motor is used for driving the grinding disc to horizontally rotate at a high speed, horizontal cutting is achieved, and the overturning and swinging power mechanism is used for driving the main beam and the auxiliary beam to be overturned upwards or downwards around the left rotation connecting part and the right rotation connecting part according to the preset angle and then to return, the above actions are repeated, overturning and swinging cutting is achieved, and therefore the grinding disc can achieve high-speed horizontal cutting and can also conduct reciprocating overturning cutting according to the preset angle; and automatic arc opening cutting is achieved, time and labor are saved, and the arc opening cutting efficiency is high.