An ultrasonic dimming system includes: a function processing module including: a first unit for generating a first electrical signal for locating a target object in a first operation state, to enable an ultrasonic transducer structure to generate first ultrasonic waves, and generating a second electrical signal for identifying finger touch position in a second operation state, to enable the ultrasonic transducer structure to generate second ultrasonic waves; a second unit for detecting reflected first ultrasonic waves to obtain target position information of the target object in the first operation state, and detecting reflected second ultrasonic waves to obtain finger touch position information in the second operation state; a third unit for controlling the ultrasonic transducer structure to perform directional sounding for the target object in the first operation state; a fourth unit for sending a control signal to the dimming glass structure to perform dimming in the second operation state.