A three-dimensional imaging system and method based on rotational scanning is disclosed. The system includes a column-shaped frame with a column-shaped side; a transceiving antenna array element arranged on the column-shaped side that transmits a micro-wave detection signal to a detected object located in the column-shaped frame and receives an echo signal reflected back from the detected object; a signal transceiving device that generates the micro-wave detection signal and sends same to the transceiving antenna array element and processes the echo signal; a rotation control device that controls rotational movement of the transceiving antenna array element so that the transceiving antenna array element transmits the micro-wave detection signal to the detected object in a plurality of angles; and a positioning trigger fixedly arranged on the column-shaped frame and configured to trigger the signal transceiving device when the transceiving antenna array element arrives at a position of the positioning trigger.