Abstract: By keeping gas metal arc welding (GMAW) arc normal position and Nd:YAG laser parallel crossing GMAW arc, refrangibility of GMAW arc to Nd:YAG laser was measured. The results indicate that when Nd:YAG laser crosses pulse GMAW arc, laser radius will decrease slightly. And the influence of pulse GMAW arc of different part to Nd:YAG is almost same. Similarly, when Nd:YAG laser crosses short-circuiting pulse GMAW arc, the radius of the laser will decrease slightly too. By considering this phenomenon from welding point of view, GMAW arc can be regarded as transparent substance and optic isotropy to Nd:YAG laser.