Al-Zn-Mg-Cu　alloys　are　important　for　aerospace　applications,　and　wire-arc　additive　manufacturing　(WAAM)　provides　a　way　to　produce　large-scale　metal　structures.　However,　research　on　the　effects　of　WAAM　thermal　cycles　on　the　microstructure　and　mechanical　properties　of　Al-Zn-Mg-Cu　alloys　is　still　lacking.　In　this　study,　quantitative　thermal　cycle　data　was　obtained　to　investigate　evolution　of　the　microstructure,　and　then　the　mechanical　behavior　of　the　as-deposited　part　was　investigated.　Results　indicated　that　the　part　mainly　contained　microcracks　(predominantly　liquation　cracks),　pores,　and　the　interdendritic　crystalline　phase,　which　decreased　the　tensile　properties.　However,　the　grain　morphology　was　dominated　by　or-ientations　with　direction　of　approximately　65　degrees　with　respect　to　the　deposition　direction,　which　led　to　better　tensile　properties　in　the　longitudinal　direction　than　in　the　transverse　direction.　In　addition,　the　micro-hardness　reached　the　maximum　(similar　to　130　HV)　after　four　to　seven　times　thermal　cycles,　which　was　mainly　attributed　to　the　Guinier-Preston　(GP)　zone.　The　continuous　high　temperature　resulted　in　the　hardness　minimum　(similar　to　104　HV),　which　was　a　significant　factor　in　forming　the　eta　＇　and　coarse　eta　phases　in　the　part.　Combined　with　the　precipitation　behavior,　hardness　of　the　whole　part　can　be　divided　into　two　zone:　un　-stable　and　stable　zone.(c)　2022　Elsevier　B.V.　All　rights　reserved.