The parallel adjustment (also called alignment or boresight) of the transmitting laser and the receiving telescope is essential for an atmospheric lidar system, which could be carried out manually or automatically. Manual alignment is time-resuming and lack of quantitative assessment. A high accurate and efficient self-aligning mechanism is urgently needed for automating the lidar system. Firstly, a brief overview of the fundamental principle of the atmospheric lidar and the importance of self-alignment is given. Next, the self-aligning methodology is reviewed, especially, the scanning method of transmitting laser and the criteria to judge the self-aligning result are introduced. In the end, the merits and drawbacks for different self-aligning methods are summarized.