This　study　aimed　to　apply　an　inverse-dispersion　calculation　method　(IDM)　to　estimate　the　emission　rate　of　volatile　organic　compounds　(VOCs)　for　the　complicated　industrial　area　sources,　through　a　case　study　on　a　petroleum　refinery　in　Northern　China.　The　IDM　was　composed　of　on-site　monitoring　of　ambient　VOCs　concentrations　and　meteorological　parameters　around　the　source,　calculation　of　the　relationship　coefficient　gamma　between　the　source＇s　emission　rate　and　the　ambient　VOCs　concentration　by　the　ISC3　model,　and　estimation　of　the　actual　VOCs　emission　rate　from　the　source.　Targeting　the　studied　refinery,　10　tests　and　8　tests　were　respectively　conducted　in　March　and　in　June　of　2014.　The　monitoring　showed　large　differences　in　VOCs　concentrations　between　background　and　downwind　receptors,　reaching　59.7　ppbv　in　March　and　248.6　ppbv　in　June,　on　average.　The　VOCs　increases　at　receptors　mainly　consisted　of　ethane　(3.1%-22.6%),　propane　(3.8%-11.3%),　isobutane　(8.5%-10.2%),　n-butane　(9.9%-13.2%),　isopentane　(6.1%　12.9%),　n-pentane　(5.1%-9.7%),　propylene　(6.1-11.1%)　and　1-butylene　(1.6%-5.4%).　The　chemical　composition　of　the　VOCs　increases　in　this　field　monitoring　was　similar　to　that　of　VOCs　emissions　from　China＇s　refineries　reported,　which　revealed　that　the　ambient　VOCs　increases　were　predominantly　contributed　by　this　refinery.　So,　we　used　the　ISC3　model　to　create　the　relationship　coefficient　gamma　for　each　receptor　of　each　test.　In　result,　the　monthly　VOCs　emissions　from　this　refinery　were　calculated　to　be　183.5　+/-　89.0　ton　in　March　and　538.3　+/-　281.0　ton　in　June.　The　estimate　in　June　was　greatly　higher　than　in　March,　chiefly　because　the　higher　environmental　temperature　in　summer　produced　more　VOCs　emissions　from　evaporation　and　fugitive　process　of　the　refinery.　Finally,　the　VOCs　emission　factors　(g　VOCs/kg　crude　oil　refined)　of　0.73　+/-　0.34　(in　March)　and　2.15　+/-　1.12　(in　June)　were　deduced　for　this　refinery,　being　in　the　same　order　with　previous　direct-measurement　results　(1.08-2.65　g　VOCs/kg　crude　oil　refined).　An　inverse-dispersion　calculation　method　was　applied　to　estimate　VOCs　emission　rate　for　a　petroleum　refinery,　being　183.5　ton/month　(March)　and　538.3　ton/month　(June).　(C)　2016　Elsevier　Ltd.　All　rights　reserved.