The invention relates to a grinding tool for a diamond. The grinding tool comprises a cylinder, a motor, a portal frame, a grinding wheel, a handle, chutes, sliders, a connecting plate, a connecting shaft, a connecting rod, a second air exhauster, a connecting pipe and a workbench. There are two chutes. The two chutes are symmetrically arranged at the front end and the rear end of the workbench. Both the two chutes are provided with sliders. The two sliders are symmetrically fixed to the front end and the rear end of the portal frame, the upper end of the portal frame is provided with the cylinder, the connecting rod is installed at the lower end of the cylinder, the lower end of the connecting rod passes through the portal frame and extends below the portal frame, and the lower end of theconnecting rod is fixedly connected with the motor. The lower end of a spindle of the motor is fixedly connected with the connecting shaft, the lower end of the connecting shaft is fixedly connectedwith the grinding wheel, the upper end of the workbench is fixed with a receiving shell, and the receiving shell is located on the right side of the portal frame. The grinding tool for the diamond isconvenient for fixing, and facilitates the collection of scraps and has adjustable height.