The invention discloses a grinding sheet machining device of diamond. The grinding sheet machining device of the diamond comprises a machine frame, a third driving mechanism, a lifting device, a motor, a rotating part and a fastener, and further comprises a moving part, a first clamping device, a second clamping device, a grinding part and a supporting plate, wherein the third driving mechanism isarranged at the top of the machine frame, the motor is arranged at the bottom of the lifting device, and the rotating part is arranged at the bottom of the motor; the bottom of the rotating part is provided with a downward protrusion, the protrusion is in threaded fit connection with the fastener, the supporting plate is horizontally arranged, the second clamping device is arranged on the supporting plate in a sliding mode, and a second driving mechanism is arranged at one end of the supporting plate; and the grinding part is arranged on the second clamping device, the moving part is arrangedon the side face of the machine frame in a sliding mode, a first driving mechanism is arranged on the moving part, and the grinding part is arranged on the first clamping device. According to the device, the process of simultaneously grinding the two end faces of a to-be-machined grinding sheet is realized, the grinding quality of the to-be-machined grinding sheet is high, and the grinding effectis good.