Excessive　intake　of　dibutyl　phthalate　(DBP)　can　cause　serious　health　problems.　Hence,　it　is　necessary　to　develop　some　simple　yet　sensitive　method　to　monitor　DBP　level　in　foods.　In　this　study,　a　competitive　multicolor　immunosensor　for　DBP　detection　has　been　proposed　based　on　the　etching　of　gold　nanorods　(GNRs)　using　naked　eyes　as　readout.　DBP　was　immobilized　on　the　surface　of　the　wells　by　physical　adsorption　(thereafter　called　solid-DBP)　and　used　to　capture　anti-DBP　antibody.　The　addition　of　target　(called　added-DBP)　competes　with　the　solid-DBP　to　combine　with　anti-DBP　antibody,　limiting　the　amount　of　anti-DBP　antibody　immobilized　on　the　plate.　A　horseradish　peroxidase　(HRP)-labeled　secondary　anti-DBP　antibody　was　then　combined　with　anti-DBP　to　form　an　antigen-antibody-secondary　antibody　competitive　complex　on　the　well　surface.　The　amount　of　HRP　immobilized　on　the　plate　is　therefore　inversely　proportional　to　the　concentration　of　DBP　in　the　sample.　3,3′,5,5′-tetramethylbenzidine　(TMB)　was　oxidized　to　produce　the　oxidized　form　of　TMB　(TMB　2+　)　in　the　presence　of　HRP,　which　etches　GNRs　to　different　degrees　within　90　s.　The　etching　results　in　vivid　color　changes　in　the　system　because　of　the　changes　in　the　localized　surface　plasmon　resonance　(LSPR)　of　the　GNRs,　and　can　be　distinguished　by　the　naked　eye.　The　value　of　the　LSPR　shift　(Δλ)　of　the　GNRs　is　inversely　proportional　to　the　concentration　of　DBP　in　the　range　of　150-2700　μg　L　-1　(0.54-9.72　μM).　The　limit　of　detection　was　determined　to　be　76　ng　L　-1　.　This　concentration-dependent　multicolor　immunosensor　offers　an　easier　approach　to　achieve　semi-quantitative　or　qualitative　detection　results　relative　to　the　traditional　system.　The　proposed　multicolor　immunosensor　can　be　applied　to　detect　DBP　in　liquor　with　satisfactory　results,　thus　providing　a　promising　platform　for　on-site　application　in　resource-poor　regions.　©2019　The　Royal　Society　of　Chemistry.