The invention discloses an ultrasonic grinding and polishing device and a use method of the ultrasonic grinding and polishing device. The ultrasonic grinding and polishing device comprises a loading assembly and a machining assembly. The loading assembly is used for holding a to-be-machined workpiece. The machining assembly conducts ultrasonic grinding on the to-be-machined workpiece. A grinding mechanism comprises an energy converter, an amplitude transformer bar and a grinding head. The grinding head is connected with the energy converter through the amplitude transformer bar. The energy converter is fixed to a grinding machine frame. Grinding blocks of different specifications are arranged and installed on a variable-diameter module, so that the grinding head can form different diameters. According to the ultrasonic grinding and polishing device and the use method of the ultrasonic grinding and polishing device, the variable-diameter module is adjusted, different specifications of grinding blocks are arranged on the variable-diameter module, so that the ultrasonic grinding and polishing device can be adapted to machining holes or arc faces of different inner diameters, the adaptability of the ultrasonic grinding and polishing device is improved, and the machining cost is lowered.