In　order　to　improve　the　ozonation　efficiency　for　the　remediation　of　PAHs　contaminated　soil,　the　performance　experiments　were　carried　out　with　quartz　sand　artificially　contaminated　with　phenanthrene.　The　byproducts　of　phenanthrene　were　detected　by　GC-MS　and　the　toxicity　was　evaluated　by　seed　germination　tests.　The　influence　of　the　particle　size　and　moisture　content　of　quartz　sand　on　the　ozonation　efficiency　was　investigated.　In　addition,　two　kinds　of　real　soil　was　used　to　compare　with　the　quartz　sand.　It　was　revealed　that　the　phenanthrene　removal　rate　reached　96％　after　600　minutes　by　using　the　ozonation　process.　Three　byproducts　of　phenanthrene,　including　9,10-phenanthrenedione,　(1,1＇-biphenyl)-2,2＇-dicarboxaldehyde,　and　(1,1＇-biphenyl)-2,2＇-dicarboxylic　acid,　were　obtained.　As　proven　by　seed　germination　tests,　the　toxicity　of　the　byproducts　was　lower　than　phenanthrene.　The　phenanthrene　was　removed　more　effectively　by　ozonation　in　the　quartz　sand　with　finer　particle　size.　The　ozonation　efficiency　was　significantly　improved　by　increasing　the　moisture　content,　which　is　assumed　to　be　related　to　the　alkalinity　of　quartz　sand.