In this paper, three methods of adding and activating weld bead elements, i.e., adding and activating the weld bead segment by segment (case A), adding and activating one weld pass after another (case B), and modified adding and activating one weld pass after another (case C), were employed to establish the corresponding simulation model of a butt joint of AA6061-T6 mid-thick plate with a double-pass weld by ABAQUS. The welding temperature field, residual stress field, and welding deformation were simulated. The heat loss of three methods in the welding simulation was tested by theoretical calculation. To verify the simulation results, the metal-inert gas (MIG) welding experiment was also performed, and the molten pool dimensions, residual stress, and welding deformation were measured. The results show both cases A and C can be effectively employed to predict residual stress, and case C can also save computing time. Case A can more accurately predict the welding deformation.