An imaging device and an imaging method are provided. An incident beam is separated into a first spectroscopic beam and a second spectroscopic beam by a spectroscopic unit and the first spectroscopic beam and the second spectroscopic beam are respectively incident on a first imaging module and a second imaging module. One of a phase detection autofocus (PDAF) mode and a contrast detection autofocus (CDAF) mode of the first imaging module is activated based on a brightness of an ambient light source. The first imaging module and the second imaging module are activated to shoot at a partially overlapping field of view (FOV) to obtain a first image and a second image. The first image and the second image are superimposed to obtain a composite image.