This review aims to show the techniques of lidar in atmospheric remote sensing, which can be utilized to draw three-dimensional maps of pollutants distribution over path lengths of the order of few kilometers. The detection limits achieve values of the order of ppb. This sensitivity and accuracy gives this method its superiority over all other physical and chemical methods of detection. Some details of this method are given for the following pollutants: NO, NO2 , SO 2, O3, HCl, C2H4, benzene and toluene, as well as atomic mercury. This work shows, for these pollutants, absorption wavelengths, differential cross sections and detection limits. In addition to dealing with the technical requirements and different designs of Lidar. On the other hand, this review study handles the characteristics of many laser sources used in lidar systems such as, Nd:YAG- laser, Dye- laser and others. Especially it concentrates on pulse energy, time duration, repetition rate and nonlinear crystals, used for frequency doubling, which broaden the working region of the lidar.