The invention discloses a piezoelectric driving-based six-leg actuator and a working method thereof, and relates to the fields of ultrasound, MEMS and piezoelectricity. Conventional motion on a planecan be achieved, and the motion capability after overturning also can be maintained. The actuator comprises a lead screw, a first phosphor bronze matrix, a titanium alloy matrix, a second phosphor bronze matrix, metal legs, a phosphor bronze round ring, an annular piezoelectric ceramic sheet, a first piezoelectric ceramic sheet group and a second piezoelectric ceramic sheet group. The working modeof the actuator comprises a normal working mode and an overturning working mode. Due to the structure characteristic of the device, the conventional motion on the plane can be achieved, the functionof maintaining the motion capability after overturning under a force majeure effect of the outside also is achieved, the device can be applied to an unstable environment to a certain extent, and meanwhile, the device has a certain develop prospect in the field of a miniature robot.