An ultrasonic cleaning system comprises a cleaning tank containing a cleaning liquid, a moving and holding device configured to move a carrier into the cleaning tank and hold the carrier in the cleaning tank, and an ultrasonic wave generator mounted in the cleaning tank. A plurality of fiber optic ferrules are mounted on the carrier and are immersed in the cleaning liquid when the moving and holding device holds the carrier in the cleaning tank. The ultrasonic wave generator is adapted to emit an ultrasonic wave into the cleaning liquid to clean the fiber optical ferrules immersed in the cleaning liquid.