The wet and dry grinding is are all suitable in the process of grinding. The wet grinding can prolong its service life and prevent burning on the work pieces. Different polishing slurry can cause the difference of several times and even more. In the course of grinding, the mechanical weariness, erosion and thermal damage are related to cooling effect. It must be noticed that CBN can react with the oxygen and vapor in the air at high temperature, and generate the Ammonia and boric acid( BN+3H2O→H3BO3+NH3). This is also called the hydrolysis, which will speed up the weariness of grinding wheels. As a result, water-soluble oil and water solution with extreme pressure additive to reduce the hydrolysis. Wet grinding with different slurry, the CBN grinding wheels’ service life will are different, the wheels cooled with pure oil is of the longest service life; wheels cooled with the water-soluble take the second place; the grinding wheels cooled with water and rust-inhibiting additive is of the lowest life.