The invention discloses an ultrasonic charging protection method and device. The method comprises steps: a multi-beam superposition mode is adopted to transmit ultrasonic charging signals and ultrasonic signals reflected after the ultrasonic charging signals meet an object are received, wherein the ultrasonic charging signals are generated according to a frequency value randomly selected in a preset frequency band; according to the ultrasonic charging signals and the reflected ultrasonic signals, whether the distance between the object and an ultrasonic beam of the ultrasonic charging device is in a shortened trend is judged; and when the distance is determined to be in the shortened trend, the transmitting power of the ultrasonic charging signals is reduced to be in a preset safe power range. The interference of ultrasonic beams to the objects is reduced, the damage caused by the high energy of the ultrasonic beams to the object is avoided, and the safety of the ultrasonic charging device is further improved.