Abstract: In order to explore the change of milling temperature in the ultrasonic assisted milling of silicon nitride ceramics, improve the quality of ceramic processing and reduce its thermal damage, the effect of spindle speed, feed speed, cutting depth and hyper vibration on the milling temperature was studied by single factor experiment method with FLIR SC325 infrared thermal imager as measuring tool. The results show that the highest temperature of the milling decreases gradually with the increase of the spindle speed, and that the faster the feed speed, the shorter the processing time and lower peak temperature in the same cutting length. The effect of cutting depth on the highest temperature of milling is periodic. The highest temperature of ultrasonic milling is slightly higher than that of common milling under the condition of dry grinding without coolant.