This study investigated the effect of the cold metal transfer-cycle step (CMT-CS) arc additive process on the quality of thin-walled parts produced with ER4043 aluminum alloy wire. The effects of welding current, welding speed, interval time and number of cycles between intervals on the macroscopic dimensions, surface quality, porosity and microstructure of thin-walled parts were investigated by using one-factor experimental method. The results show that the CMT-CS process can further precisely control the deposition process and reduce the heat input compared with the conventional CMT process. Different heat inputs and material amounts under different process parameters produce melt pools of different sizes, which in turn affect the macroscopic dimensions and surface quality of the arc additive thin-walled parts. The CMT-CS process has superior porosity suppression than the CMT process. The transverse specimens exhibited a tensile strength of (146.59±3.52) MPa and an elongation of (22.29±3.13)%, which was significantly improved compared with that of the cast parts. The study shows that through the reasonable optimization of CMT-CS process parameters, the morphology and microstructure of thin-walled parts can be effectively controlled, which provides a reference basis for the application of CMT-CS process and the arc additive manufacturing of 4043 aluminum alloy.