In order to explore the vibration characteristics of grinding head of internal gear NC grinding machine,taking the grinding head as research object, its threedimensional solid model was built. Based on the finite element simulation software ANSYS, the dynamic characteristics of the grinding head under prestress were analyzed. The natural frequencies and corresponding vibration modes of the grinding head were obtained, and the weak links were optimized, which improved the performance of the grinding head. A test platform for vibration characteristics of the grinding head was built. Vibration signals of the grinding head under different working conditions were collected. The vibration mechanism of the grinding head was explored by using the comparative analysis method of time domain signal and frequency domain signal.The test results show that the vibration amplitude of the grinding head is larger at lower frequency. Finally, some reasonable suggestions were put forward to reduce the vibration of the grinding head.