The effects of bath composition, process conditions and other factors on the internal stress and hardness of Ni-W alloy coating were investigated, and the coating with low internal stress and high hardness was prepared for tribochemical polishing of diamond. The effects of sodium tungstate concentration, complexing agent concentration, solution PH, saccharin sodium concentration on the internal stress, tungsten content, hardness and deposition rate of the coating were investigated by single experiment, and the leveling effect of different additives on the coating roughness was explored. Finally, under the conditions of sodium tungstate 40 g/L, sodium citrate 120 g/L, saccharin sodium 1 g/L, and solution PH of 6, a Ni-W alloy disk with hardness of 713 hv and thickness of 0.7 mm was prepared by using the reverse pulse method and salicylaldehyde as the leveling agent. The polishing disc is used to conduct tribochemical polishing of diamond, and the process conditions are studied. When the speed of the polishing disc is 8000 rpm (linear speed 19.3 m/s), and the pressure is about 4.4 MPa, the polishing effect is good, and the removal rate is 5.56 μ M/min, and the grinding ratio reaches 0.394, and the surface roughness is Ra 3.693 nm. Compared with the cast iron disk, the performance of nickel tungsten alloy disk is much higher.