China　has　started　to　focus　on　the　reduction　in　pollutants　from　diesel　vehicles　with　high　emission　intensities　in　recent　years.　Therefore,　it　is　essential　and　valuable　to　conduct　a　deep　and　detailed　exploration　of　the　reduction　potential　from　diesel　vehicles　and　compare　the　abatement　effect　from　different　control　measures　in　upcoming　decades.　This　study　attempted　to　estimate　the　present　emissions　of　four　conventional　pollutants　from　diesel　vehicles　by　applying　the　Computer　Program　to　Calculate　Emissions　from　Road　Transport　(COPERT)　model,　and　to　predict　the　future　emission　trends　under　different　scenarios　during　2019-2030,　taking　the　Beijing-Tianjin-Hebei　(BTH)　region　as　the　case　study　area.　In　addition,　we　analyzed　the　emission　reduction　potential　of　diesel　vehicles　and　compared　the　reduction　effects　from　different　control　measures.　The　results　showed　that　the　CO　and　NOX　emissions　from　diesel　vehicles　in　this　region　could　increase　by　104.8%　and　83.9%,　respectively,　given　no　any　additional　control　measures　adopted　over　the　next　decade.　The　largest　emission　reduction　effect　could　be　achieved　under　the　comprehensive　scenario,　which　means　that　vehicular　diesel　emissions　in　2030　could　decrease　by　74.8-94.0%　compared　to　values　in　2018.　The　effect　of　emission　reduction　under　the　emission　standards＇　upgrade　scenario　could　cause　a　gradual　increase　and　achieve　a　19.8-82.6%　reduction　for　the　four　pollutants　in　2030.　Furthermore,　the　new　energy　vehicle　promotion　scenario　could　achieve　a　considerable　reduction　effect.　It　could　also　offer　better　emission　reduction　effects　under　the　highway　to　railway　scenario　for　Tianjin　and　Hebei　provinces.　The　old　vehicle　elimination　scenario　could　have　a　considerable　reduction　effect,　but　only　in　the　short　term.　Furthermore,　emission　reductions　could　be　mainly　influenced　by　heavy　diesel　trucks.　These　results　can　provide　scientific　support　to　formulate　effective　reduction　measures　to　diesel　vehicles　for　policy　makers.