Abstract: The inner hole of silicon nitride ceramic are turned with PCD tools.Firstly, the removal mechanisms of silicon nitride ceramic is studied, which mainly includes the brittle removal and the ductile removal, and the brittle removal is the main removal mechanism.Secondly, the influences of rake angle, cutting speed, cutting depth and feed rate on the cutting force are studied.Resultsshow that the influence of rake angle on cutting force is not obvious, and that the cutting force increases with the increase of cutting speed, cutting depth and feed rate.The radial force is greater than the feed force and the main cutting force.Finally, the influences of the parameters on the surface roughness are mainly studied.The results show that the most significant impact factor on surface roughness is feed rate, followed by cutting speed and cutting depth.The rake angle has little impact.When they are 0.08mm/r, 32.97m/min, 0.10 mm and-5°, respectively, there is a better comprehensive balance between surface roughness and tool life.