To solve the issue of non-destructive surface manufacturing of KDP crystal and further improve the polishing quality and efficiency of the water dissdution polishing method, the influence of dielectrophoresis on the water dissdution polishing slurry is studied. The polishing method of dielectrophoretic assisted water dissdution is proposed, and finally, an ultra-smooth surface is obtained. The motion behavior of the polarized droplets was simulated by the software of finite element analysis in this paper. To verify the polishing principle, the verification platform to observe the adsorption behavior of the slurry under the action of dielectrophoresis force was built. Through the numerical simulation, the influence of different electrode shapes on the dielectrophoresis force of micro-droplets was studied, and the optimal electrode shape parameters were obtained. A test platform was built to verify the efficiency and quality improvement effects of dielectrophoresis on the water dissdution polishing. The analysis of the motion behavior of the water dissdution polishing slurry and the micro-droplets in it show that:the micro water droplets were deformed under the action of dielectrophoresis force and gather near the crystal surface, thereby the number of micro-droplets involved in disdissdution during polishing was increased and the removal rate was increased; at the same time, slurry was adsorbed by the upper electrode to prolong the action time of the slurry on the crystal surface, the slurry rejection rate was reduced, and further, the polishing efficiency was improved; the double-helical structure electrode has the largest electric field gradient, which can make the water droplets receive the largest dielectrophoretic force and gather on the crystal surface. The polishing experiment results show that:after polishing for 20 minutes, the surface roughness of KDP crystal by the traditional water dissdution polishing was reduced from Ra 590 nm to 1.637 nm, while the surface roughness of KDP crystal by the dielectrophoresis assisted water dissdution polishing was reduced to 1.365 nm. Compared with water dissdution polishing, the efficiency of dielectrophoresis assisted water dissdution polishing with double spiral electrode arrangement was increased by 24%, and a smooth surface can be obtained faster. With the aid of the dielectrophoresis effect, the quality and efficiency of KDP crystal water dissdution polishing are improved.