Abstract: Through using the equipment designed independent， the ability of ultrasonic to generate bubbles in different conditions is investigated. The effect of ultrasonic on the gas hold-up of solution in the state of inflation is also investigated. The result showed: the ability of ultrasonic to generate bubbles is directly related to the amount of gas dissolved in the solution， the power of ultrasonic has a considerable effect on the quantity of the gas produced by ultrasonic cavitation， the volume of bubbles generated by ultrasonic cavitation under the booster of 28kHz is bigger than the booster of 20kHz. When the ultrasonic acts on the solution of MIBC， the volume of gas produced by cavitation varies little. Under the condition of aeration， the ultrasonic can enhance the gas hold-up of solution effectively.