Abstract: Potassium dihydrogen phosphate (KH₂PO₄ or KDP), an recognized optical crystal, has been widely used in laser nuclear fusion projects due to its good quality of large electro-optic coefficient and large diameter (≥ 400 mm).From growth to processing into optical element, it requires procedures of cutting, precision machining, ultra-precision machining, coating and so on, and the processing period is long.In this paper, the grinding process of the KDP crystal is carried out using the vertical spindle face grinding machine.The influences of different particle sizes resin bonded diamond wheels (D7, D36, D91, D151) on the surface roughness and surface micro-topography under different processing parameters (spindle speed, feed speed, grinding depth) are compared.The feasibility of KDP crystal grinding is studied which lays the foundation for realization of grinding instead of turning (polishing) and shortening the manufacturing cycle of KDP optical elements.