This paper presents a piezoelectric-driven stepping rotary actuator based on the inchworm motion. With the help of nine piezoelectric stacks and the flexure hinges, the designed actuator can realize large rotary ranges and high rotary speed with high accuracy. Three kinds of working units that compose the actuator are described and calculated: the clamping unit to hold the rotor, the adjusting unit to preload the piezoelectric stacks and the driving unit to produce the driving torque. To test the working performance, a prototype actuator was fabricated, and the experimental results indicate that the minimum stepping angle is 4.95μrad when the driving voltage is 20V and the frequency is 1Hz, the maximum output torque is 93.1Nmm under the driving voltage of 100V and the maximum velocity can be 6508.5μrad/s when the frequency reaches 30Hz. The experimental results verify that the proposed actuator can realize different stepping angles and rotation speeds with high accuracy under different driving voltages and frequencies.