The invention discloses a quantitative feeding device of an ultrasonic vibrating screen. The quantitative feeding device of the ultrasonic vibrating screen comprises a stock bin. The bottom of the stock bin is connected with the top of a hopper through a solenoid valve A. A solenoid valve B is arranged at the bottom of the hopper. A high material level sensor and a low material level sensor are arranged on the inner wall of the hopper independently. The high material level sensor is arranged above the low material level sensor. A rotating disk is arranged below the hopper. A rotating shaft isfixedly arranged at the center of the rotating disk. One end of the rotating shaft is fixedly connected with the output shaft of a gear motor through a coupling. The other end of the rotating shaft isrotationally connected with a bearing block arranged on the rack of the vibrating screen. A fixed outer ring is arranged on the outer side of the rotating disk. A sliding rail is arranged on the inner wall of the fixed outer ring. According to the quantitative feeding device of the ultrasonic vibrating screen, because the hopper, the rotating disk, the fixed outer ring, quantitative holes and a lifting platform are arranged, and it is solved that the feeding quantity of the feeding device of a traditional ultrasonic vibrating screen is hard to control, and materials cannot be replenished intoa hopper in time.