An imaging device and an imaging method by millimeter wave 3D holographic scanning are disclosed. In an embodiment, the millimeter wave 3D holographic scanning imaging device may include: a conveying apparatus configured to convey an object located thereon in a first direction; and at least one millimeter wave transceiving module arranged beside the conveying apparatus, each configured to be enabled to scan the object when the conveying apparatus conveys the object through the respective millimeter wave transceiving module, wherein each millimeter wave transceiving module is arranged to have its longitudinal direction extend in a direction intersecting the first direction, and includes a millimeter wave transceiving antenna array for transceiving millimeter wave signals.