Provided is a special automatic positioning mechanism for aluminum ingot laser marking. The automatic positioning mechanism comprises a fixed component frame (1), a longitudinal slide rail (4) and a transverse slide rail (7), and the longitudinal slide rail (4) and the transverse slide rail (7) can respectively move up and down and move back and forth relative to a fixed component. A cylinder (2) is installed below the frame, and the cylinder (2) is connected with a slider on the longitudinal slide rail (4) through a cylinder connection head. The slider on the longitudinal slide rail (4) is connected and equipped with a cantilever beam (10) through a bolt. The cantilever beam (10) is connected with the rear end of a movable bracket (6) through a spring (9). A universal joint (13) at the front end of the movable bracket (6) is connected with the front end of the cantilever beam (10) through a shaft. The movable bracket (6) is equipped with the transverse slide rail (7). A transverse cylinder (5) is installed on the transverse slide rail (7), and is connected with a slider through a cylinder connection head (12). A fixing plate (11) is fixed on the slider on the transverse slide rail (7), and the fixing plate is equipped with a rotary sleeve (8) and a laser scanning head (3).