The invention discloses a standing wave demonstration method. The method comprises the steps that a. a standing wave demonstration device is designed; b. an ultrasonic atomization module is turned on to ultrasonic-atomize liquid into fogdrops, and the fogdrop are introduced into a cylinder through a fogdrop inlet tube; and c. a sound wave generating device and a frequency converter are turned on, and the frequency converter is controlled to adjust the frequency of sound waves emitted by the sound wave generating device. According to the standing wave demonstration device, the right end of the cylinder is provided with the sound wave generating device; the frequency converter is connected with the sound wave generating device; the left end of the cylinder is connected with the ultrasonic atomizing module through the fogdrop inlet tube; an elongated ejection notch is axially arranged at the upper part of the cylinder wall; and a transparent baffle plate is symmetrically arranged on front and rear sides of the elongated ejection notch. According to the invention, a traditional demonstration instrument which displays standing waves by igniting a combustible gas is abandoned; the fogdrops after ultrasonic atomization are used to display the standing waves; safety hidden fire trouble can be avoided; and the cylinder is prevented from burning hot.