A laser anti-reflection device includes a polarizing beam splitter, a λ/4 wave plate and an absorber disposed in an outgoing light path of a laser emitting linearly polarized light with a wavelength of λ. The linearly polarized light from the laser passes through the polarizing beam splitter and the λ/4 wave plate in turn to become a circularly polarized light beam. Part of the circularly polarized light beam is then reflected by a workpiece to be processed along the original light path and passes the λ/4 wave plate to become a linearly polarized light beam with a polarization direction vertical to that of the outgoing linearly polarized light beam. The vertical polarized beam passes the polarizing beam splitter, deviates from the light path of the outgoing linearly polarized light beam and reaches the absorber. The laser anti-reflection device prevents reflected light from damaging the laser from high power lasers.