Dry ultrasonic cleaning is the removal of surface dust particles by high-speed airflow and ultrasonic waves. It does not require the installation of cooling and drying equipment, nor does it require high-cost consumables such as high-purity gases or chemical detergents. This report explores the design of ultrasonic waves generated by dry ultrasonic cleaning machines. The ultrasonic wave is generated by increasing the flow velocity through the variable cross-section air flow path, so that the air wave frequency is greater than 20 kHz to form ultrasonic waves. The flow analysis of the COMSOL software simulation dry ultrasonic cleaning machine is used to provide the design basis for the cleaning head. The influence of different expansion chamber shape on the pressure and air velocity is discussed. The increase of the inlet flow velocity is beneficial to the increase of the outlet flow velocity.