Al-Zn-Mg-Cu　alloys　are　widely　used　in　aerospace　structures　because　of　their　excellent　performances.　To　improve　the　poor　mechanical　performance　of　the　Al-Zn-Mg-Cu　arc　additive　manufactured　deposit,　heat　treatments　were　used　for　the　enhancement　of　mechanical　performances.　The　microstructure　of　the　deposits　was　improved　after　heat　treatment　due　to　the　decomposition　of　intermetallic　compounds.　Meanwhile,　the　solid　solution　of　alloying　elements　and　the　phase　transformation　led　to　two　strengthening　mechanisms:　solid　solution　strengthening　and　the　precipitation　strengthening.　The　performance　enhancement　of　the　deposits　was　most　significant　under　the　T6　heat　treatment.　The　horizontal　and　vertical　strength　increased　to　513　and　504　MPa,　respectively,　and　the　hardness　increased　to　205　HV　with　more　uniformly　distribution　in　the　vertical　direction.