Rapid　detection　of　body　fluid　severe　acute　respiratory　syndrome　coronavirus　2　(SARS-CoV-2)　antibody　is　an　effective　strategy　for　infection　therapeutic　effect　of　coronavirus　disease　(COVID-19).　Most　detection　methods　require　relatively　large　equipment,　which　limited　their　on-site　application.　Lateral　flow　immunoassay　(LFIA)　can　be　used　to　qualitative　antibody　detection　based　on　the　aggregation　of　gold　nanoparticles　(Au　NPs),　which　exhibits　just　one-color　change　and　cannot　realize　rapid　quantitative　detection　without　the　help　of　additional　equipment.　In　this　study,　a　high-resolution　multicolor　colorimetric　strategy　was　developed　and　applied　to　assessing　antibody　concentration　at　a　glance　based　on　etching　of　gold　nanorods　(Au　NRs).　Firstly,　SARS-CoV-2　recombinant　antigen　was　immobilized　on　the　surface　of　the　96-wells.　Then,　horseradish　peroxidase　(HRP)-labeled　second　antibody　combined　with　antibody　to　form　an　antigen-antibody-secondary　antibody　complex　on　the　well　surface,　which　has　direct　relationship　with　antibody　concentration　in　the　sample　and　can　be　used　to　oxidize　3,3＇　,5,5＇-tetramethylbenzidine　(TMB)　to　form　TMB2+　at　the　presence　of　HRP.　The　generation　of　TMB2+　efficiently　etch　Au　NRs　to　produce　multicolor　solution.　The　etching　result　in　vivid　color　changes　in　the　system　has　a　relationship　with　the　amount　of　SARS-CoV-2　IgM　antibody.　Under　the　optimal　conditions,　the　proposed　strategy　exhibited　a　linear　response　in　the　5.00-200　IU　concentration　range,　and　a　detection　limit　of　1.29　IU　for　SARS-CoV-2　IgM　antibody,　with　high　sensitivity　and　specificity.　This　assay　is　prospective　for　the　on-site　semi-quantitative　visual　detection　of　SARS-CoV-2　IgM　antibody　concentration　in　the　COVID-19　therapeutic　process.