Abstract: Objective In response to the urgent need for wire arc additive manufacturing of Al-Cu-Mg-Ag heat-resistant alloy, arc-depositing process based on cold metal transfer (CMT) technology is used to deposit Al-Cu-Mg-Ag alloy in a single layer with multiple process modes. Moreover, its depositing effect is comprehensively compared with that of the commonly used 2319 alloy to reflect arc-depositing characteristics of the heat-resistant alloy. Methods Arc atmosphere, transition characteristics of molten droplets and flow characteristics of molten pool during the depositing process are thoroughly analyzed by high-speed camera images and real-time arc signals. Results The results showed that under CMT + P process mode, width and height of the deposited layers are uniform, and interlayer bonding is better, the mode is the best depositing process mode. Addition of Ag element makes molten pool of Al-Cu-Mg-Ag alloy have better fluidity and spreading during the arc-depositing process, and reflux of molten pool is more adequate during the depositing process, which results in the smooth surface of the formed deposited layer. Ag and Mg elements make Al-Cu-Mg-Ag alloy have special physical property (better conductivity), which greatly improves stability of arc, resulting in a more stable and smoother transition of molten droplets. Conclusion It has been proven that Al-Cu-Mg-Ag alloy can achieve good formation of straight-walled component with wire arc additive manufacturing under CMT technology.