The invention relates to a laser marking machine for metal bars. The laser marking machine comprises a triaxial linear module (1), and the triaxial linear module is arranged on one side of a steel billet conveying mechanism (2). A laser marking device (3) is arranged on the triaxial linear module (1). The triaxial linear module (1) comprises a transverse moving rail (11), and a transverse moving sliding seat (12) is arranged on the transverse moving rail (11). A lifting rail (13) is arranged on the transverse moving sliding seat (12), and a lifting sliding seat (14) is arranged on the liftingrail (13). A longitudinal moving rail (15) is arranged on the lifting sliding seat (14), and a longitudinal moving sliding seat (16) is arranged on the longitudinal moving rail (15). The laser markingdevice (3) is arranged on the longitudinal moving sliding seat (16). According to the laser marking machine, etching marking is carried out through laser, and therefore the marking requirement can bemet fast, the labor intensity is greatly reduced, the marking efficiency is improved, and the laser marking machine can meet the marking requirements of the bars of different specifications.