This paper reports a new rotary thermal micro-actuator. This new thermal actuator uses a pair of powerful silicon-polymeric composite benders to actuate a magnetic head slider into a rotation when the expandable polymer elements are resistively heated. The advantage is the rotary micro-actuator design can move the read/write head slider with a larger lateral displacement by using a new T-shape central hinge joint as compared to the previous translational design. The experimental results demonstrate that the prototyped device can reach up 314nm displacement by a 4V step voltage. The 1st mechanical resonance frequency has been pushed up to 35 kHz. Simulation shows that the micro-actuator can be subjected to 1000G shock loading under non-operation mode. The large displacement, high resonance frequency and robust shock resistance make the rotary thermal micro-actuator be very suitable for a wide range of precise positioning systems applications including dual-stage positioning systems in disk drives and resonance switches in microsystems.