Heavy　metal-organic　pollutants　compound　pollution　at　industrial　legacy　sites　and　have　caused　damage　to　the　ecological　environment　and　human　health　during　recent　decades.　In　view　of　the　difficulty　and　high　cost　of　post-contamination　remediation,　it　is　worth　studying,　and　practically　applying,　cutoff　walls　to　reduce　the　spread　of　pollution　in　advance.　In　this　study,　field-scale　studies　were　carried　out　at　e-waste　dismantling　legacy　sites　in　Taizhou,　Zhejiang　Province　of　China,　through　the　process　of　site　investigation,　numerical　simulation,　and　cutoff　wall　practical　application.　Firstly,　the　concentrations　and　spatial　distributions　of　Pb,　Cd　and　polychlorinated　biphenyls　(PCBs)　and　poly　brominated　diphenyl　ethers　(PBDEs)　were　identified　in　both　soil　and　groundwater.　Then,　potential　dispersal　routes　of　key　combined　contaminants　(Pb　and　PCBs)　at　the　soil-groundwater　interface　were　systematically　studied　through　numerical　simulation　applying　Visual　MODFLOW-MT3DMS.　One　site　was　chosen　to　predict　the　barrier　effect　of　differently　sized　cutoff　walls　based　on　the　migration　path　of　compound　pollutants.　A　protocol　for　a　cutoff　wall　(50　m　length　x　2　m　width　x　3　m　height)　was　finally　verified　and　applied　at　the　real　contaminated　site　for　the　blocking　of　compound　pollutant　diffusion.　Further,　the　groundwater　quality　of　the　contaminated　site　was　monitored　consecutively　for　six　months　to　ensure　the　durability　and　stability　of　barrier　measures.　All　pollutant　indicators,　including　for　Pb　and　PCB　complex　pollutants,　were　reduced　to　below　the　national　Grade　IV　groundwater　standard　value,　achieving　environmental　standards　at　these　polluted　sites　and　providing　possibilities　for　land　reuse.　In　summary,　this　field-scale　test　provided　new　ideas　for　designing　cutoff　walls　to　block　the　diffusion　of　complex　pollutants;　it　also　laid　a　basis　for　the　practical　application　of　cutoff　walls　in　pollution　prevention　and　control　of　complex　contaminated　sites　and　for　soil-groundwater　environmental　protection　at　industrial　heritage　sites.