The invention relates to the technical field of laser antenna etching, in particular to a laser etching method for an RFID tag antenna and a system for implementing the method. The system comprises a laser, a beam expanding mirror, a galvanometer, a focusing lens, cooling equipment and a worktable; a tag antenna to be machined is placed on the cooling equipment; a plastic layer at the bottom of the RFID tag antenna to be machined is in close contact with the cooling equipment; the RFID tag antenna to be machined and the cooling equipment are fixed to the worktable together through a clamp; a laser beam which is output by the laser is expanded through the beam expanding mirror, is deflected through the galvanometer, is finally focused through the focusing lens and acts on an aluminium foil plating layer on the upper surface of the tag antenna to be machined. A non-woven fabric water absorbing pad is arranged at the bottom of the RFID tag antenna, so that the machining temperature of the plastic layer is effectively reduced, the plastic layer is prevented from being molten, and a laser etching technology can be applied to the field of RFID tag antennae.