An imaging device based on millimeter wave three-dimension 3D holographic scanning, the imaging device comprising: a conveying apparatus configured to convey an object located thereon in a first direction to pass through at least one respective millimeter wave transceiving module (4, 5) arranged beside the conveying apparatus; and the at least one millimeter wave transceiving module (4, 5), each being configured to be enabled to scan the object when the object passes through the respective millimeter wave transceiving module (4, 5), wherein each millimeter wave transceiving module (4, 5) is arranged to have its longitudinal direction extend in a direction intersecting the first direction, and comprises a millimeter wave transceiving antenna array for transceiving millimeter wave signals, wherein the at least one millimeter wave transceiving module (4, 5) is arranged beside the conveying apparatus, the millimeter wave transceiving antenna array comprises a column of millimeter wave transmitting antennas and a column of millimeter wave receiving antennas, and the two columns are arranged in parallel; the imaging device being characterized in that it further comprises: a position sensor configured to sense a position of the object on the conveying apparatus; an indicating apparatus configured to issue an indication when it is determined that a distance of the object toward a millimeter wave transceiving module (4, 5) is less than a predetermined value, and issue an indication when it is determined that the distance of the object apart from the millimeter wave transceiving module (4, 5) is more than a predetermined value, based on a sensing result of the position sensor. a conveying apparatus configured to convey an object located thereon in a first direction to pass through at least one respective millimeter wave transceiving module (4, 5) arranged beside the conveying apparatus; and the at least one millimeter wave transceiving module (4, 5), each being configured to be enabled to scan the object when the object passes through the respective millimeter wave transceiving module (4, 5), wherein each millimeter wave transceiving module (4, 5) is arranged to have its longitudinal direction extend in a direction intersecting the first direction, and comprises a millimeter wave transceiving antenna array for transceiving millimeter wave signals, wherein the at least one millimeter wave transceiving module (4, 5) is arranged beside the conveying apparatus, the millimeter wave transceiving antenna array comprises a column of millimeter wave transmitting antennas and a column of millimeter wave receiving antennas, and the two columns are arranged in parallel; the imaging device being characterized in that it further comprises: a position sensor configured to sense a position of the object on the conveying apparatus; an indicating apparatus configured to issue an indication when it is determined that a distance of the object toward a millimeter wave transceiving module (4, 5) is less than a predetermined value, and issue an indication when it is determined that the distance of the object apart from the millimeter wave transceiving module (4, 5) is more than a predetermined value, based on a sensing result of the position sensor. a position sensor configured to sense a position of the object on the conveying apparatus; an indicating apparatus configured to issue an indication when it is determined that a distance of the object toward a millimeter wave transceiving module (4, 5) is less than a predetermined value, and issue an indication when it is determined that the distance of the object apart from the millimeter wave transceiving module (4, 5) is more than a predetermined value, based on a sensing result of the position sensor.