Atomic filter is an optoelectronic device used for optical spectra filtering and optical frequency discrimination. As the working frequency of this device is determined by atomic or molecular transitions,the atomic fitler has ultra-high stability of working frequency,ultra-narrow working band-pass,good out-of-band suppression,high transmission,and so on. Therefore,the atomic filters are widely used in the fields of lidar and optical communication,and have enhanced the performance of lidar and optical communication systems. The principle,structure,development and some applications of the atomic filters are introduced and discussed.