Abstract: 4043 aluminum alloy thin-walled parts were obtained by arc additive manufacturing under the conditions of cold metal transition with addition of pulse (CMT+P). The forming performance of thin-walled parts prepared under different parameters were compared. The microstructure and tensile properties of thin-walled parts with good forming performance were studied, and compared with those prepared by CMT process. The results show that when the welding speed was 8 mm·s^-1 and wire feeding speed was 4 m·min^-1, the forming performance of thin-walled parts prepared by CMT+P process was the best, and the forming effect was close to that prepared by CMT process. The microstructure of single layer of thin-walled parts prepared by CMT+P process consisted of fine-grained area in the upper layer and coarse-grained area in the lower layer, and there were coarse columnar dendrites growing through the interface between weld beads. The microstructure prepared by CMT process was fine columnar crystals with uniform distribution. The tensile properties of thin-walled parts prepared by CMT+P process were better than those under CMT process condition. The fracture modes of longitudinal and transverse tensile samples under CMT+P process condition were both ductile fracture and anisotropy percentage of longitudinal and transverse tensile streagth was only 4%, indicating there was no anisotropy in mechanical properties of thin-walled parts.