A　process　variant　of　variable　polarity　plasma　arc　welding　(VPPAW),　that　is,　the　pulsed　plasma　gas　VPPAW　process,　was　developed.　The　pulsed　plasma　gas　was　transmitted　into　the　variable　polarity　plasma　arc　through　a　high-frequency　solenoid　valve　to　modify　the　output　of　the　plasma　arc.　The　collection　of　arc　electrical　characteristics,　arc　shapes,　and　weld　formation　from　VPPAW,　double-pulsed　VPPAW　(DP-VPPAW),　and　pulsed　plasma　gas　VPPAW　(PPG-VPPAW)　was　carried　out　to　examine　if　the　pulsed　plasma　gas　was　able　to　play　a　positive　role　in　improving　the　stability　and　quality　of　the　VPPAW　process.　The　arc　voltage　shows　that　the　pulsed　plasma　gas　had　a　greater　influence　on　the　electrode　positive　polarity　voltage.　The　lower　the　plasma　gas　frequency　was,　the　lower　the　arc　voltage　fluctuation　frequency　was　and　the　greater　the　arc　voltage　fluctuation　amplitude　was.　From　the　arc　image,　it　could　be　observed　that　the　arc　core　length　had　a　short　decrease　during　the　general　rising　trend　after　plasma　gas　was　turned　on.　The　arc　core　width　only　had　a　slight　change　due　to　the　restriction　of　the　torch　orifice.　Compared　with　pulsed　current　wave,　the　pulsed　plasma　gas　could　better　enhance　the　fluidity　of　the　molten　pool　to　reduce　porosity　during　aluminum　keyhole　welding.