Based on the robot automatic grinding platform, the experimental study on the grinding process of zirconia coating was carried out in order to control the coating thickness and surface roughness properly and improve coating surface quality. Based on Preston removal equation, the material removal model was established. The effect of main parameters on the removal depth was studied by single factor experiments. The optimum process parameters and process steps were determined by orthogonal experiment and utilized on the zirconia coating of throat seal of aero-engine. The experimental results show that the removal depth of the material increases with the increasing of grinding force and speed of grinding tool, and decreases with the increasing of feed speed in a certain range. The grinding force has the more influence and the grinding angle has less influence on the removal depth. The force control method is adopted to achieve the quantitative and uniform removal, the coating thickness and surface quality are consistent, the processing efficiency is improved significantly, which verifies the practicability and advantages of the robot automatic grinding system.