In this paper, the impulse pressure distribution in the ultrasonic water bath with a thin tube is mainly explored and the ultrasonic capillary phenomenon is explained. The reasons for the rise of the liquid level in the tube are the impulse pressure generated when the cavitation bubble generated by the surface tension and cavitation effect collapses. We simulated the distribution of ultrasonic sound pressure in the water bath by COMSOL, calculated the cavitation bubble radius and its change rate with time under different sound pressure amplitude conditions based on MATLAB, and calculated the magnitude of the impulse pressure in integration. In the experiment, by changing the position of the bottom of the thin tube, the influence of the punching pressure on the rising height of the liquid level was explored, and the ultrasonic capillary phenomenon was well explained compared with the theoretical curve, and the experimental results were consistent with the ultrasonic cavitation theory.