The invention discloses a method of controlling mass transfer of Micro-LEDs by using ultrasonic standing waves, which includes the following steps: a transfer substrate is moved in order to make Micro-LED wafers needing to be transferred aligned with a laser emitter; the laser emitter emits a laser beam to make the Micro-LED wafers detach from the elastic layer of the transfer substrate and fall into the ultrasonic control range, and sound pressure nodes make the Micro-LED wafers suspended; a radiation end face and a reflection end face move on a guide rail to change the spacing between the Micro-LED wafers; an ultrasonic transducer stops emitting ultrasonic waves, and the Micro-LED wafers fall onto the corresponding positions of a target substrate under the action of gravity; and after surface mounting, the next surface mounting process continues. The method of the invention has the advantages as follows: the transfer efficiency is high; the method is not limited by the surface mounting spacing of the Micro-LEDs on the target substrate; and the yield of Micro-LED wafer packaging is high.