Both　agricultural　and　construction　machinery　are　important　non-road　sources　of　atmospheric　pollution,　with　total　hydrocarbons　(THC),　nitrogen　oxides　(NOx)　and　particulate　matter　(PM)　emissions　accounting　for　more　than　60%　of　the　total　emissions　from　all　non-road　mobile　sources　in　China.　However,　there　exist　relatively　few　efforts　to　establish　the　emission　inventory　for　these　machineries.　This　study　attempted　to　estimate　and　predict　air　pollutant　emissions　from　agricultural　and　construction　diesel　machinery,　using　the　Beijing-Tianjin-Hebei　(BTH)　region　as　the　case　study　area.　The　results　show　that　total　emissions　of　PM10,　PM2.5,　THC,　NOx,　CO　and　SO2　in　2015　were　41.10,　38.80,　86.14,　520.41,　379.01　and　17.32　Kt　respectively.　The　contribution　of　agricultural　machinery　was　slightly　higher　than　that　of　construction　machinery,　accounting　for　60-71%　of　the　total.　Moreover,　emissions　of　various　pollutants　(except　SO2)　from　agricultural　machinery　were　mainly　distributed　in　central　Hebei　(Cangzhou,　Shijiazhuang　and　Baoding),　while　emissions　from　construction　machinery　were　mainly　distributed　in　Beijing　and　Tianjin.　The　prediction　suggest　that　the　total　emissions　of　agricultural　and　construction　diesel　machinery　in　the　BTH　region　would　increase　by　6%　in　2020　and　9%　in　2025.　Moreover,　pollutant　emissions　from　construction　machinery　would　contribute　from　29%　to　40%　in　2015　to　34%-61%　in　2025.　These　results　could　provide　important　information　for　making　effective　mitigation　measures　of　non-road　mobile　sources.　(C)　2020　Elsevier　Ltd.　All　rights　reserved.