LiDAR is a kind of active detection technology, which can acquire the three-dimensional spatial informa-tion of the target accurately and quickly. Due to its unique technical advantages in object recognition, classification, high-precision 3D imaging and measurement, the application scope and development prospect of LiDAR are quite broad. In this article, the principles of various LiDAR detection and 3D imaging systems are introduced, and the for-eign and domestic development status of single point scanning, linear array sweeping and planar array 3D imaging LiDAR systems are summarized and sorted out. Meanwhile, their technical characteristics, advantages and disad-vantages in different platforms and application fields such as spaceborne, airborne and vehicular platforms are compared and analyzed. Recently, 3D imaging LiDAR is gradually developed from single point scanning to small array scanning, line array sweep and array flash imaging. At the same time, the single photon detection technology is becoming mature and the detection sensitivity is getting higher and higher. With the development of modern de-tection technology more and more inclined to the fusion detection of various sensors, the development of 3D imaging is also inclined to the combination of active and passive imaging to obtain more abundant target information.