Abstract: Q235 low carbon steel was welded by plasma-MIG(metal inert gas)welding process and the influence of welding parameters on weld appearance and transfer mode of droplet were studied. The results indicate that plasma-MIG welding is superior over regular MIG welding on the aspects of increasing welding efficiency, reducing welding spatter and gas pore.When the other conditions are the same, with increasing of plasma current the weld width increaecs but the weld penetration and transfer mode of droplet change little. With increasing of MIG weding current the cluster of closed lines in the U-I phase graph are more concentrative and the transfer mode of droplet is short circuiting transfer, globular transfer and spray transfer in turn.