Anew tool vibration system is developed for the ultrasonic elliptical vibration cutting, and it is applied to ultraprecision cutting of hardened steel in the present research. A method and a device to remove crosstalks between the two directional vibrations are developed, so that the two directional vibrations can be controlled independently. Then, a controller is developed to keep the elliptical vibration to have a desired locus, where the amplitudes of the two directional vibrations, phase shift between them are kept to be desired values and the vibration frequency is locked to an average of their resonant frequencies. The developed vibration control system is applied to utraprecision diamond turning of hardened steel, and an ultraprecise steel mirror with a shape accuracy of about 0.1 μm is achieved.