As a novel auto-stereoscopic three-dimensional (3D) display technology, integral imaging is able to acquire complete 3D information of the 3D scene and reconstruct it. Thus, integral imaging is one of the most promising technologies of the glasses-free 3D displays. In the integral imaging 3D information acquisition process, different perspectives of the 3D scene are recorded to generate the elemental image array to be the 3D content for the integral imaging display. On the other hand, the integral imaging 3D acquisition can be a multi-dimensional information pickup approach applied to the detection and imaging of occluded scenes, target recognition, two-dimensional (2D) / 3D information encryption and microscopic 3D imaging fields. The basic principles, different types of the integral imaging 3D information acquisition approaches, and real-time 3D information acquisition technologies were reviewed in this paper. Some challenging problems and future development trend of the technology were also discussed.