Wire　arc　additive　manufacturing　(WAAM)　of　Al-Zn-Mg-Cu　alloys　often　leads　to　poor　strength　and　ductility　due　to　microstructure　defects,　significantly　limiting　its　application.　This　study　employed　friction　stir　processing　(FSP)　to　reduce　porosity　and　break　up　continuous　coarse　second　phases　along　the　grain　boundaries.　By　adding　high-entropy　alloy　(HEA)　particles　with　good　wettability　during　FSP,　Al-Zn-Mg-Cu　alloy　components　with　simultaneously　improved　strength　and　ductility　were　produced.　The　results　indicated　that　the　grain　structure　transformed　from　columnar　to　equiaxed　and　was　refined　to　2.3　mu　m　owing　to　the　dynamic　recrystallization　of　FSP　and　the　particle-stimulated　nucleation　of　HEA　particles,　while　the　continuous　second　phase　was　fragmented　into　nanoscale　precipitates　uniformly　distributed　in　the　matrix,　acting　as　dislocation　movement　barriers.　The　newly　formed　Ni3Al　precipitates　second　phases　ensure　good　ductility　due　to　its　low　lattice　mismatch　with　Al　matrix.　Additionally,　the　HEA　particles　maintained　strong　interfacial　bonding　with　Al　matrix,　with　an　interfacial　layer　thickness　of　similar　to　400　nm.　The　FSP-HEA　treated　components　showed　increased　hardness　(151.8　HV),　ultimate　tensile　strength　(374.3　+/-　20.4　MPa),　and　elongation　(10.6　%　+/-　1.6　%)　compared　to　the　WAAM　as-deposited　state.　This　study　provides　guidance　for　the　improvement　of　microstructural　defects　and　the　simultaneous　enhancement　of　the　strength　and　ductility　of　high-strength　Al　alloy　WAAM　components.