A circuit for 3D ultrasound imaging systems includes multiple sensor units, multiple unit circuits and multiple row sharing circuits. The unit circuits are connected with the sensor units respectively. Each row of unit circuits share a row sharing circuit. Each unit circuit includes a first electrically controlled switch, a second electrically controlled switch and a control circuit. Each row sharing circuit includes a signal transmission bus, a signal receiving bus and a row main control circuit. The signal transmission bus and the signal receiving bus of each row sharing circuit extend through a corresponding row of unit circuits. The row main control circuit of each row is configured to transmit main control signals, transmission control signals and receiving control signals to a corresponding row of unit circuits so as to select the corresponding sensor units to transmit or receive ultrasound signals.
