The range-gated laser active imaging technology is a research focus because it has many advantages such as long range, independent of environment illumination, suppressing the backscattering, and capable of three-dimensional (3D) imaging. We introduce the principle of the gated-viewing technology, and analyze the representative researches in China and abroad on application the technology of long-range surveillance and 3D imaging, including typical systems, technical characteristics and application status. Finally, several future research trends of the range-gated viewing technology are given.