Compared　with　on-road　vehicles,　emission　from　ships　is　one　of　the　least-regulated　anthropogenic　emission　sources　and　non-negligible　source　of　primary　aerosols　and　gas-phase　precursors　of　PM2.5.　The　Bohai　Rim　Region　in　China　hosts　dozens　of　large　ports,　two　of　which　ranked　among　the　top　ten　ports　in　the　world.　To　determine　the　impact　of　ship　emissions　on　the　PM2.5　concentrations　over　this　region,　two　parts　ofworks　have　been　conducted　in　this　study.　First,　a　detailed　ship　emission　inventory　with　high　spatiotemporal　resolution　was　developed　based　on　Automatic　Identification　System　(AIS)　data.　Then　the　WRF/Chem　model　was　applied　to　modeling　the　impact　of　ship　emissions　by　comparing　two　scenarios:　with　and　without　ship　emissions.　The　results　indicate　that　the　total　estimated　ship　emissions　of　SO2,　NOX,　PM10,　PM2.5,　CO,　HC,　and　CO2　from　Bohai　Rim　Region　in　2014　are　1.9　x　10(5),　2.9　x　10(5),　2.6　x　10(4),　2.4　x　10(4),　2.5　x　10(4),　1.2　x　10(4),　and　1.3　x　10(7)　tonnes,　respectively.　The　modeling　results　indicate　that　the　annual　PM2.5　concentrations　increased　by　5.9%　on　land　areas　of　Bohai　Rim　Region　(the　continent　within　115.2　degrees　E-124.3　degrees　E　and　36.1　degrees　N-41.6　degrees　N)　due　to　ship　emissions.　The　contributions　show　distinctive　seasonal　variations　of　contributions,　presenting　highest　in　summer　(12.5%)　followed　by　spring　(6.9%)　and　autumn　(3.3%),　and　lowest　in　winter　(0.9%).　The　contribution　reaches　up　to　10.7%　along　the　shoreline　and　down　to　1.0%　200　km　inland.　After　examining　the　statistics　of　the　modeling　results　during　heavy　and　non-heavy　haze　days　in　July,　it　was　found　that　6　out　of　9　cities　around　the　Bohai　Rim　Region　were　observed　with　higher　contributions　from　ship　emissions　during　heavy　haze　days　compared　with　non-heavy　haze　days.　These　results　indicate　that　the　impacts　of　ship　emissions　on　the　ambient　PM2.5　are　non-negligible,　especially　for　heavy　haze　days　for　most　coastal　cities　in　the　Bohai　Rim　Region.　(C)　2017　Elsevier　B.V.　All　rights　reserved.