Abstract: A method and system for automatically aligning a high power laser. The high ower laser train includes an unstable resonator cavity and two turning mirrors to direct the pointing of the output laser beam. The autoalignment system is designed to perform two alignment tasks, the maintenance of output beam pointing stability and the establishment of resonator cavity mode control, by precisely adjusting the orientation of the end mirrors of the resonator cavity and the two turning mirrors. A HeNe laser, located at the output end of the high power laser train, propagates an alignment beam back along the laser train, parallel to the high power laser train. The alignment beam is divided into two separate alignment beams by means of a mirror splitter. One of the beams is directed on an optical alignment path which includes the two turning mirrors and is delimited by two null position detectors, one on an end mirror of the resonator cavity and one at the output end of the high power laser train.