The variation of arc characteristics with respect to its profile under Ar+2%CO₂, Ar+18%CO₂ and argon gas shielding and the stability of gas shielding with variation in pulse parameters have been studied by video-graphy of arc environment during P-GMA weld deposition using mild steel filler wire. The effect of pulse parameters has been studied by considering their hypothetically proposed summarized influence defined by a dimensionless factor, φ=[(I_b/I_p)ft_b], mean current and arc voltage. The measured root diameter, projected diameter and length have been measured and correlated to the P-GMA welding parameters under different gas shielding. It has been observed that the arc characteristics with respect to its shape and spreading over the weld significantly vary with φ, mean current and arc voltage giving due consideration to the shielding environment. The use of Ar+2%CO₂ gas shielding appreciably reduces the D_R but enhances the D_P and L with respect to that observed under Ar+18%CO₂ and argon gas shielding.