The invention discloses a machining device used for machining an anti-clamp groove of an ultrathin diamond cutting piece. The machining device comprises a workpiece clamping unit, an electrolytic power supply, spraying nozzles, an electrolytic circulation filter unit, a conductive grinding head moving guide unit, a grinding rotation unit, a fixed platform and a grinding force loading unit; a workpiece is connected to an anode of the electrolytic power supply, the two conductive grinding heads are connected with a cathode of the electrolytic power supply, and the two conductive grinding heads are symmetrically arranged on both sides of the workpiece; and four springs with the same specification are adopted to apply same flexible pressing force to the left conductive grinding head and the right conductive grinding head, the two spraying nozzles are mounted on the inclined upper portion of the tangent position of the two conductive grinding heads and the workpiece, and circulating electrolyte supplying is conducted through the electrolytic circulation filter unit. According to the machining device used for machining the anti-clamp groove of the ultrathin diamond cutting piece, machining of the double-face annular anti-clamp groove is achieved through the machining mode of simultaneous rotating of the workpiece and the two conductive grinding heads, the machining precision and thesurface quality of the anti-clamp groove are improved, symmetry of the anti-clamp groove is better, and the machining efficiency of the workpiece is higher.