At　present,　Al-Cu-Mg-Ag　heat-resistant　alloys　have　become　suitable　materials　for　lightweight　heat-resistant　structures　of　high-speed　crafts.　Wire　arc　direct　energy　deposition　(WA-DED)　technology　offers　a　suitable　solution　to　the　great　challenge　of　integrated　rapid　manufacturing　of　large-complex　Al-Cu-Mg-Ag　alloy　components.　Unfortunately,　there　are　few　reports　on　the　use　of　WA-DED　technology　for　the　fabrication　of　Al-Cu-Mg-Ag　alloys,　and　the　arc-deposition　characteristics　of　Al-Cu-Mg-Ag　alloys　are　not　yet　clear.　In　this　work,　the　droplet　transition　features　and　arc　characteristics　of　Al-Cu-Mg-Ag　alloy　during　different　Cold　Metal　Transfer　(CMT)　modes　were　investigated　to　illustrate　the　special　deposit　characteristics　induced　by　its　unique　material　properties.　The　surface　tension　coefficient　of　Al-Cu-Mg-Ag　alloys　at　certain　high　temperatures　was　quantitatively　calculated.　The　common　2319　alloy　with　similar　Al-Cu　content　was　specifically　used　as　a　reference　to　better　reflect　the　deposit　characteristics　of　Al-Cu-Mg-Ag　alloy.　The　results　show　that　the　surface　tension　coefficient　of　the　Al-Cu-Mg-Ag　alloy　is　5.6　%　lower　than　that　of　2319　alloy　in　the　temperature　interval　from　1400　to　1650　degrees　C.　Al-Cu-Mg-Ag　alloy　is　more　prone　to　produce　more　Mg　and　Ag　vapors　with　low　ionization　energies　during　WA-DED,　which　promotes　stable　burning　of　the　arc　and　improves　the　electrical　conductivity　of　the　arc　atmosphere,　with　a　slight　decrease　in　voltage　during　deposition,　despite　the　increase　in　arc　length.　The　more　stable　arc　atmosphere　enables　the　more　uniform　droplet　transition　period　and　the　more　stable　and　smooth　transition　process　of　droplets,　while　the　lower　surface　tension　coefficient　facilitates　the　flow　of　the　molten　pool　to　promote　the　formation　of　a　smoother　deposited　layer　surface.　These　promising　results　will　contribute　to　the　application　of　WA-DED　for　the　efficient　manufacturing　of　Al-Cu-Mg-Ag　aerostructural　components.