Abstract: Digital welding power supply was used for carrying out Bead-On-Plate welding experiments by single pulsed, double pulsed, and trapezoid modulated pulsed gas metal arc welding. Base current and welding speed were adjusted to investigate the effect of current parameters on heat input of the above welding methods. Effect of different current parameters on solidification structure of welds was also discussed. Results indicate that grain refinement of welds can be achieved by lower heat input, and hardness of welded joints can be improved by faster welding speed.