ASTM A516 grade 70 low alloy steels is a pressure vessel grade steels .The present research investigates the effect of GMAW (Gas Metal Arc Welding) process parameters on the bead geometry and HAZ area on 6mm thick plate through bead on plate experiments. The GMAW process parameters such as voltage, welding speed, wire feed rate and their effect are studied. The Taguchi L9 orthogonal array design is applied for this approach. In this design the three factors with three levels voltage (17, 18,19V), welding speed (600,800,1000mm/min), wire feed rate (50, 60,70mm/s) are used for investigation. ANOVA (Analysis of variance) was used in this study to find the most significant parameters. The results from Taguchi analysis indicated that the parameters under consideration have an influence in the bead geometry and HAZ area. ANOVA result showed that the parameter wire feed rate was the most significant parameter which influence bead height and depth of penetration .The Bead Width is dominated by the voltage influence and wire feed rate being the most influential parameter on HAZ area.