In this study, the hybrid arc shape, thermal cycling curve, voltage-current characteristics, and weld formation of 7A52 high-strength armor aluminum alloys welded by a variable polarity plasma arc (VPPA) combined with gas metal arc welding (GMAW) (VPPA-GMAW) were investigated and compared with those of 7A52 aluminum alloys welded by GMAW. The influence of the hybrid arc coupling mechanism on the GMAW arc was studied. The results show that the electromagnetic coupling of the VPPA-GMAW hybrid arc has a dynamic compression effect on the GMAW arc. The GMAW arc is compressed parallel to the axis of the welding direction during the VPPA direct current electrode negative (DCEN) period. In addition to the ampere force of the hybrid arc magnetic field, the GMAW arc is also subjected to the hot extrusion of the hybrid arc’s coupling zone, and the arc shrinkage is greater during the direct current electrode positive (DCEP) period. With increasing VPPA current, the compression effect of the GMAW arc is enhanced. An 11-mm-thick 7A52 aluminum alloy is one-sided welded by cooperative control of the hybrid arc welding parameters.