This paper presents the design, simulation and fabrication of an mm-scale air-driven microturbomachine. The circumferential-flow turbomachine has a plain-shaped structure with an overall size of 8×8×3mm3. The predicted formulas for driving torque and driving power are deduced by analyzing the working condition of the model. Finite element simulation is carried out to determine the driving torque and driving power. Turbine and stator are fabricated using UV-LIGA technique, while other components using pension micromachining. Test results of assembled prototype show that under the air-flow speed of 80m/s, no-load and load rotation speed are 10kr/min and 9.5kr/min respectively, and the output power is 326.57µW. The results indicate micro turbomachine is potential power source for the micro system.